Anonymization is a technique that removes or modifies all identifiers in a data set to prevent or limit the identification of the data subjects. Anonymization is the IT privacy practitioner's best recommendation for an organization that uses analytics derived from archived transaction data to create individual customer profiles for customizing product and service offerings, as it would protect the privacy of the customers by reducing the linkability of the data set with their original identity, and also comply with the data minimization principle that requires limiting the collection, storage and processing of personal data to what is necessary and relevant for the intended purposes. Anonymization would also preserve some characteristics or patterns of the original data that can be used for analysis or customization purposes, without compromising the accuracy or quality of the results. The other options are not as effective as anonymization in this situation. Discontinuing the creation of profiles is not a feasible or desirable option, as it would prevent the organization from achieving its business objectives and providing value to its customers. Implementing strong access controls is a security measure that restricts who can access, view or modify the data, but it does not address the issue of collecting or retaining more personal data than necessary or relevant. Encrypting data at rest is a security measure that transforms plain text data into cipher text using an algorithm and a key, making it unreadable by unauthorized parties, but it does not address the issue of collecting or retaining more personal data than necessary or relevant, and may require additional security measures to protect the encryption keys or certificates1, p. 75-76 Reference: 1: CDPSE Review Manual (Digital Version)

The greatest privacy risk for client-side application processing is an employee loading personal information on a company laptop. Client-side application processing refers to performing data processing operations on the user's device or browser, rather than on a server or cloud. This can improve performance and user experience, but also pose privacy risks if the user's device is lost, stolen, hacked, or infected with malware. An employee loading personal information on a company laptop is exposing that information to potential threats on the client-side, such as unauthorized access, use, disclosure, modification, or loss. Therefore, an organization should implement appropriate security measures to protect personal information on client-side devices, such as encryption, authentication, authorization, logging, monitoring, etc. Reference: : CDPSE Review Manual (Digital Version), page 153

The best answer is D. Mutual certificate authentication.
A comprehensive explanation is:
Mutual certificate authentication is a method of mutual authentication that uses public key certificates to verify the identities of both parties in a two-way communication. A public key certificate is a digital document that contains information about the identity of the certificate holder, such as their name, organization, domain name, etc., as well as their public key, which is used for encryption and digital signature. A public key certificate is issued and signed by a trusted authority, called a certificate authority (CA), that vouches for the validity of the certificate.
Mutual certificate authentication works as follows:
Both parties have a public key certificate issued by a CA that they trust.
When they initiate a communication, they exchange their certificates with each other.
They verify the signatures on the certificates using the CA's public key, which they already have or can obtain from a trusted source.
They check that the certificates are not expired, revoked, or tampered with.
They extract the public keys from the certificates and use them to encrypt and decrypt messages or to generate and verify digital signatures.
They confirm that the identities in the certificates match their expectations and intentions.
By using mutual certificate authentication, both parties can be confident that they are communicating with the intended and legitimate party, and that their communication is secure and confidential.
Mutual certificate authentication is often used in conjunction with Transport Layer Security (TLS), a protocol that provides encryption and authentication for network communications. TLS supports both one-way and two-way authentication. In one-way authentication, only the server presents a certificate to the client, and the client verifies it. In two-way authentication, also known as mutual TLS or mTLS, both the server and the client present certificates to each other, and they both verify them. Mutual TLS is commonly used for secure web services, such as APIs or webhooks, that require both parties to authenticate each other.
Virtual private network (VPN), Secure Shell (SSH), and Transport Layer Security (TLS) are all technologies that can help to ensure the identities of individuals in a two-way communication are verified, but they are not methods of mutual authentication by themselves. They can use mutual certificate authentication as one of their options, but they can also use other methods, such as username and password, pre-shared keys, or tokens. Therefore, they are not as specific or accurate as mutual certificate authentication.
Reference:
What is mutual authentication? | Two-way authentication1
How to prove and verify someone's identity2
Identity verification - Information Security & Policy3

Beacons use Bluetooth low-energy (BLE) wireless technology to transmit information to nearby devices that have Bluetooth enabled. By disabling Bluetooth services on the mobile device, the user can prevent beacons from detecting and tracking their location and sending them unwanted messages or advertisements. This can help protect the user's privacy and avoid potential security risks from malicious beacons. Disabling location services, enabling Trojan scanners, or enabling antivirus for mobile devices are not effective ways to address threats to mobile device privacy when using beacons as a tracking technology, because they do not prevent the communication between beacons and the mobile device.
Reference:
Beacon Technology: What It Is and How It Impacts You1
What Does It All Mean: Beacon Technology, GPS and Geofencing2

The best way to maintain the quality of personal data is to implement routine automatic validation, which is a process of checking the accuracy, completeness, consistency, and timeliness of the data using automated tools or scripts. Routine automatic validation can help identify and correct any errors, anomalies, or discrepancies in the data, as well as ensure that the data meets the specified quality standards and requirements. Routine automatic validation can also help improve the efficiency and reliability of the data processing and analysis12.
Reference:
CDPSE Exam Content Outline, Domain 3 - Data Lifecycle (Data Quality), Task 2: Implement data quality measures3.
CDPSE Review Manual, Chapter 3 - Data Lifecycle, Section 3.2 - Data Quality4.