A customer who is nervous, uneasy, or in a hurry to cash a large cashier's check may be trying to launder money or evade reporting requirements. The teller should complete the transaction as normal, but also flag the customer's account for further monitoring and review. The teller should look for any unusual or suspicious patterns of activity, such as frequent large cash transactions, transfers to or from high-risk jurisdictions, or transactions that do not match the customer's profile or expected behavior. The teller should also document the transaction and the customer's demeanor, and report any findings or concerns to the appropriate authority within the bank.
The teller should not confer with the bank's account going forward, as this may alert the customer to the bank' s suspicion or compromise the investigation. The teller should not file a SAR on the customer, unless there are other grounds to suspect money laundering or terrorist financing, as this may be premature or unnecessary.
The teller should not file a CTR on the customer by the end of the day, unless the transaction exceeds the threshold of $10,000, as this is a legal requirement for cash transactions in the US.
[ACAMS Study Guide for the CAMS Certification Examination, 6th Edition], Chapter 4: Conducting or Supporting the Investigation Process, pp. 103-104, 107-108.
Suspicious Activity Reporting - Overview, Federal Financial Institutions Examination Council, April 2018, pp. 1-2, 4-5.
Currency Transaction Reporting - Overview, Federal Financial Institutions Examination Council, April 2018, pp. 1-2, 4-5.
17 AML Analyst Interview Questions and Answers, CLIMB, July 15, 2022.

* A (Enhanced due diligence): EDD is a key control at onboarding for high-risk customers, involving deeper scrutiny, additional documentation, and approval layers to address increased ML/TF risk.
* "High-risk customers must be subject to enhanced due diligence during onboarding to ensure a thorough understanding of potential ML/TF risks."(CAMS 6th Edition, CDD/EDD for High-Risk Customers) References:
CAMS 6th Edition, CDD/EDD
FATF Recommendations 10, 12

The next course of action for the anti-money laundering officer to take is to determine if there is a readily identifiable cause for the increase in compliance deficiencies. This could involve analyzing the data, interviewing the staff, reviewing the procedures, or conducting a root cause analysis. The anti-money laundering officer should try to find out if the deficiencies are due to human error, system failure, policy ambiguity, training gap, external factors, or any other reason. By identifying the cause, the anti-money laundering officer can then take appropriate corrective or preventive measures to address the issue and improve the compliance performance.
CAMS Study Guide - 6th Edition, Chapter 6, pages 171-172
CAMS Certification Exam Outline, Domain 3, Task 3.1, Skill 3.1.2
Anti-Money Laundering & Know Your Customer eBook, Chapter 5, pages 63-64 Summary of the Global Anti-Money Laundering Know Your Customer Policy, page 3

Casinos and gambling institutions are highly vulnerable to money laundering because they allow the conversion of cash into chips, checks, or electronic credits, which can later be redeemed as "clean" funds.
Option A (Correct): A privately held company funding multiple patrons' betting accounts is highly suspicious and may indicate:
Structuring/smurfing, where multiple individuals are used to move illicit funds.
Third-party money laundering, where the real source of funds is obscured.
Trade-based money laundering, if linked to non-gaming businesses.
Why Other Options Are Incorrect:
Option B (Incorrect): Placing multiple bets on the same event is not inherently suspicious unless linked to fraudulent betting patterns.
Option C (Incorrect): Large chip purchases in cash may require reporting, but they do not necessarily indicate money laundering.
Option D (Incorrect): Transferring winnings to another operator may be unusual, but not automatically suspicious unless the amount is large and unjustified.
Common Money Laundering Techniques in Casinos:
Chip Walking - Buying chips with illicit funds and cashing them out later as "clean" funds.
Casino Account Transfers - Using multiple accounts or third-party accounts to move funds.
High-Value Gambling with No Loss Intent - Betting on both sides of an event to ensure clean withdrawal of funds.
Best Practices for Casino AML Compliance:
Monitor suspicious large transactions and third-party funding activities.
Perform enhanced due diligence (EDD) on high-risk patrons.
File Suspicious Transaction Reports (STRs) for unusual gambling activity.
Reference:
FATF Report on Money Laundering in Casinos
6th EU AML Directive (6AMLD) on Gaming & Gambling AML Risks
FinCEN Guidance on Casino AML Compliance