Financial Intelligence Units (FIUs) are national agencies that collect, analyze, and disseminate information on suspicious or unusual financial activity, such as money laundering and terrorist financing, to relevant authorities. One of their main functions is to disseminate the results of their analysis to law enforcement agencies in a timely manner, so that they can initiate investigations or prosecutions. This is also one of the standards set by the Financial Action Task Force (FATF), the global body that sets the anti-money laundering and counter-terrorist financing (AML/CFT) policies and recommendations. The other options are not the primary responsibilities of FIUs, although they may perform them as part of their mandate or in cooperation with other agencies.
References:
What are Financial Intelligence Units (FIUs)? | Dow Jones
Financial Intelligence Units: An Overview - IMF
Financial Intelligence Units - Egmont Group
FATF Recommendation 29 - Financial Intelligence Units (page 17)
Reference:
https://knowledgehub.transparency.org/assets/uploads/helpdesk/Financial-Intelligence-Units_Design-Mandate-P

the specialist should inform the bank's senior legal advisor of the situation and seek guidance on how to handle the legal request and the internal memos. The specialist should not take any action that could compromise the integrity of the legal request, the bank's anti-money laundering program, or the specialist's own professional obligations. The specialist should not place the memos in his personal files, as this could be seen as hiding or tampering with evidence. The specialist should not ask the bank president to document his instructions, as this could create a conflict of interest or a perception of undue influence. The specialist should not call the law enforcement agent and suggest he modify the legal request, as this could be seen as interfering with the investigation or tipping off the account holder.
References:
Legal Sector Affinity Group (LSAG) Anti-Money Laundering Guidance for the Legal Sector (January
2021) p. 1321
ACAMS: Certified Anti-Money Laundering Specialist | ACAMS2
Anti-Money Laundering - The Law Society of Singapore3

The bank should request a formal letter be submitted to verify the validity of the request, as this is the best practice to ensure compliance with the law and protect customer privacy. The bank should not confirm or deny the existence of a customer relationship, nor provide any information without proper authorization. The bank should also not inform the board of directors before responding to the request, as this could compromise the confidentiality of the investigation or alert the customer.
References:
ACAMS CAMS Certification Video Training Course, Module 2: Compliance Standards for Anti-Money Laundering (AML) and Combating the Financing of Terrorism (CFT), Section 2.3: Data Protection and Privacy, Slide 10 ACAMS CAMS Certification Study Guide, 6th Edition, Chapter 2: Compliance Standards for Anti-Money Laundering (AML) and Combating the Financing of Terrorism (CFT), Page 51 Reference: https://ico.org.uk/for-organisations/guide-to-freedom-of-information/receiving-a-request/