Churning is the prohibited practice of excessive trading in a customer’s account—often a discretionary account—primarily to generate commissions or other compensation for the broker rather than to meet the customer’s investment objectives. That makes B correct. The core elements regulators look for are: control over the account (discretion or de facto control), excessive frequency/volume relative to the customer’s profile, and an intent or effect of generating commissions at the customer’s expense. Churning violates ethical standards and anti-fraud principles because it places the broker’s interest ahead of the customer’s.

Choice A, kiting, typically refers to exploiting the time it takes for checks to clear by writing checks against insufficient funds—this is a banking/payment fraud concept, not excessive trading. Choice C, freeriding, refers to buying securities in a cash account and then selling them before paying for them, using sale proceeds to cover the purchase—this is linked to cash account payment violations and Regulation T concepts, not overtrading. Choice D, front running, involves trading ahead of a customer order or block trade (or ahead of research) to profit from an expected price move—again, not the same as excessive trading to generate commissions.

The SIE emphasizes prohibited practices in customer accounts, including excessive trading, conflicts of interest, and supervisory obligations. Recognizing churning is essential because it is a classic example of misconduct where the customer’s best interest is subordinated to compensation incentives.