Three individuals enter a casino and use cash to purchase chips worth 20,000 USD.

The potential red flag that alludes to money laundering is option B, where the trio engage in minimal gambling and combine the funds to request a casino cheque for the chips presented. This behavior is indicative of structuring, which involves breaking down large transactions into smaller ones to avoid detection by the casino and regulatory authorities. The fact that the trio only used a small amount of chips to play games, and then combined their funds to request a casino cheque, raises suspicions that they may be attempting to disguise the origin of their funds.