Ongoing Due Diligence: FATF emphasizes the importance of continuous monitoring of business relationships and transactions. This involves regularly assessing the risk associated with a customer and ensuring that the information remains up-to-date. It includes monitoring transactions for any suspicious activity or red flags.
Beneficial Owners: Identifying beneficial owners is crucial, but it must be done with verification of their true identity. This is part of the initial due diligence process.
Risk Assessment: Conducting risk assessments is essential, but it is not specific to customer due diligence.
Risk assessment applies broadly to anti-money laundering (AML) programs.
Products and Services Suitability: While understanding the suitability of products and services is relevant, it is not a direct measure within customer due diligence.
References:
Anti-Money Laundering Specialist (the 6th edition) resources.
FATF 40 Recommendations (Recommendation 10: Customer Due Diligence).1
CFATF Technical Articles (Customer Due Diligence Measures).2

The board of directors is ultimately responsible for ensuring that the financial institution has an effective anti- money laundering program that complies with the applicable laws and regulations. If the institution receives a regulatory enforcement action, the board should take prompt and corrective actions to address the deficiencies and mitigate the risks of further violations or penalties. One of the most important actions is to instruct the compliance officer to develop a plan to remediate the institution's anti-money laundering program, which should include a root cause analysis, a gap assessment, a timeline, and a budget. The board should also monitor the implementation and progress of the remediation plan, and communicate with the regulators on a regular basis.
The other options are not appropriate actions for the board of directors to take in response to a regulatory enforcement action. Terminating the compliance officer and staff may not solve the underlying issues of the anti-money laundering program, and may create more disruption and instability. Purchasing and installing a new suspicious activity monitoring system may not be necessary or sufficient to address the deficiencies, and may entail additional costs and challenges. Hiring an attorney to protest the enforcement action may not be in the best interest of the institution, and may antagonize the regulators and escalate the situation.
CAMS Certification Package - 6th Edition | ACAMS, Chapter 5: Risk Management, Section 5.2: Regulatory Examinations and Enforcement Actions, pp. 171-174.
CAMS Certifications: How to Get CAMS Certified | ACAMS, CAMS Examination Preparation Guide, Section 3: Regulatory Compliance, pp. 23-24.

According to the CAMS Certification Package - 6th Edition1, the ultimate responsibility for an institution's anti-money laundering program rests with the institution's board of directors. The board of directors is responsible for creating a culture of compliance, approving the AML policies and procedures, appointing the AML compliance officer, overseeing the implementation and effectiveness of the AML program, and ensuring adequate resources and training are provided to the staff. The board of directors is also accountable for any deficiencies or violations of the AML program and must take corrective actions when necessary.
CAMS Certification Package - 6th Edition | ACAMS

Sanctions screening and transaction monitoring rules are two of the most common controls that FIs use to identify suspicious money-laundering activity. Sanctions screening is the process of checking customers, transactions, and counterparties against various lists of sanctioned individuals, entities, and countries issued by national and international authorities. Sanctions screening helps FIs to avoid doing business with or facilitating the activities of those who are involved in terrorism, proliferation, human rights violations, or other criminal activities. Transaction monitoring rules are the criteria or scenarios that FIs use to detect unusual or potentially suspicious patterns of transactions or behaviors of customers or accounts. Transaction monitoring rules help FIs to identify transactions that deviate from the expected norms, such as large cash deposits, frequent wire transfers, or transactions with high-risk jurisdictions. Transaction monitoring rules also help FIs to comply with their reporting obligations, such as filing Suspicious Activity Reports (SARs) or Currency Transaction Reports (CTRs).
= ACAMS CAMS Certification Video Training Course, Chapter 4: Developing an Effective Anti-Money Laundering Program, Section 4.2: Customer Identification Program (CIP) and Customer Due Diligence (CDD); Money laundering and terrorist financing, Section: Anti Money Laundering (AML) regulations; The Three Stages Of Money Laundering And How Money Laundering Works, Section: How to Prevent Money Laundering.