A "red flag" in the context of financial crime is a warning sign indicating potential money laundering or criminal activity. (Option B)
Financial institutions, such as banks and investment firms, are required to monitor transactions to detect suspicious activities. A red flag can include a wide range of activities or patterns, such as unusual large transactions, frequent transfers among accounts without a clear business purpose, or discrepancies between the customer's perceived wealth and their account activity.
These warning signals are vital in identifying and preventing illicit activities, as they indicate that further investigation may be necessary to ensure compliance with legal and regulatory standards designed to prevent financial crimes.