The best approach to optimize resources when both internal and external audit teams are reviewing the same IT general controls area is to leverage the work performed by external audit for the internal audit testing. This can avoid duplication of efforts, reduce audit costs and enhance coordination between the audit teams. The internal audit team should evaluate the quality and reliability of the external audit work before relying on it.
Ensuring both the internal and external auditors perform the work simultaneously is not an efficient use of resources, as it would create redundancy and possible interference. Requesting that the external audit team leverage the internal audit work may not be feasible or acceptable, as the external audit team may have different objectives, standards and independence requirements. Rolling forward the general controls audit to the subsequent audit year is not a good practice, as it would delay the identification and remediation of any control weaknesses in a high-risk area. References: ISACA, CISA Review Manual, 27th Edition, 2018, page
247

Write access to production program libraries presents the greatest risk when granted to a new member of the system development staff. Production program libraries contain executable code that runs on live systems and supports critical business functions. Write access allows a user to modify or delete existing programs, or add new programs to the library. If a user were to make unauthorized or erroneous changes to production programs, it could cause serious disruptions, errors, or security breaches in the organization's operations.
Therefore, write access to production program libraries should be restricted to authorized personnel only, and subject to strict change management controls.

The security architecture of an online application is a design that describes how various security components and controls are integrated and configured to protect the application from internal and external threats. When auditing the security architecture of an online application, an IS auditor should first review the location of the firewall within the network, as this determines how effectively the firewall can filter and monitor the traffic between different network segments and zones. The firewall standards, configuration, and firmware version are also important aspects to review, but they are secondary to the location of the firewall.

Due professional care is the obligation of an IS auditor to exercise the appropriate level of skill, competence, and diligence in performing an audit. It also requires the IS auditor to comply with the relevant standards, guidelines, and ethical principles of the profession. Completing an engagement by email only may compromise due professional care, as it may limit the IS auditor's ability to obtain sufficient and appropriate evidence, to communicate effectively with the auditee and other stakeholders, and to perform adequate quality assurance and review procedures. The other options are not as relevant as due professional care, as they relate to specific aspects of an audit, such as proficiency (the knowledge and skills of the IS auditor), sufficient evidence (the quantity and quality of the audit evidence), and reporting (the presentation and communication of the audit results). References: CISA Review Manual (Digital Version), Domain 1: The Process of Auditing Information Systems, Section 1.2 ISACA IT Audit and Assurance Standards

Encryption is the process of transforming information into an unreadable form using a secret key, so that only authorized parties can access it. Encryption would protect the confidentiality of information sent in email messages, as it would prevent unauthorized parties from intercepting and reading the messages. Secure Hash Algorithm 1 (SHA-1) is a cryptographic hash function that produces a fixed-length output from an input.
SHA-1 does not encrypt information, but rather verifies its integrity by detecting any changes or modifications. Digital signatures are electronic signatures that use encryption and hash functions to authenticate the identity of the sender and the integrity of the message. Digital signatures do not protect the confidentiality of information, but rather ensure its authenticity and non-repudiation. Digital certificates are electronic documents that contain the public key and identity information of an entity, such as a person, organization or device. Digital certificates are issued by trusted third parties called certificate authorities (CAs). Digital certificates do not protect the confidentiality of information, but rather enable secure communication and encryption by verifying the identity and public key of an entity. References:
* : [Encryption Definition]
* : [Secure Hash Algorithm 1 (SHA-1) Definition]
* : [Digital Signature Definition]
* : [Digital Certificate Definition]