The correct answer is B, because it describes a method of money laundering known as structuring or smurfing. This is when a customer or a group of customers break down large amounts of illicit funds into smaller transactions that are below the reporting threshold, and then send them to another customer or entity, often in another country. This way, they avoid triggering any suspicion or regulatory reporting by the bureau de change or money services business (MSB) that processes the wire transfers.
Structuring or smurfing is a common technique used by money launderers to move funds across borders and disguise their origin and destination.
The other options are not necessarily indicative of money laundering, although they may require further investigation depending on the circumstances and the risk profile of the customers and countries involved.
Option A describes a regular and small wire transfer that may be legitimate, such as a remittance to a family member or a friend. Option C describes a large volume of wire transfers that may be related to a seasonal or business activity, such as a holiday or a trade event. Option D describes a series of small wire transfers that may be coincidental or random, and do not necessarily add up to a significant amount.
References:
ACAMS CAMS Certification Video Training Course - 6th Edition1
Exam CAMS: Certified Anti-Money Laundering Specialist (the 6th edition)2 ACAMS CAMS Study Guide - 6th Edition, Chapter 2, pages 36-37
https://www.acams.org/wp-content/uploads/2019/09/ACAMS-CAMS-Study-Guide-6th-Edition-Chapter-2.pdf