In a remedial practice session, the fact pattern is framed this way. Treat the facts as a straight Series 63 application question. A broker-dealer deposits a customer's funds into the firm's general operating account. This is an example of:

Why B — Commingling of funds, which is prohibited

Under NASAA model rules and USA Section 502, commingling customer funds with a broker-dealer's own funds is a prohibited practice. Customer funds must be maintained in separate accounts to protect them from the firm's creditors and to ensure proper accounting. Mixing customer and firm funds creates significant risks of misuse and loss. This version tests the same concept with a different fact pattern wrapper.