Final answer:
A salesperson, like Terry, is prohibited from assigning clients to an unlicensed assistant, but can refer clients to another licensed salesperson or inform the clients of the situation and request their understanding and patience.
Step-by-step explanation:
When a salesperson, like Terry, needs emergency surgery but has several clients for whom he's actively working, there are limitations on what actions he can take. In this case, Terry is prohibited from assigning the clients to an unlicensed assistant (option B) as it is against the regulations.
However, Terry can refer the clients to another licensed salesperson in the same brokerage (option A) or inform the clients of the situation and request their understanding and patience (option C). Completing all pending transactions before the surgery (option D) is also a responsible action for Terry to take, but it is not a prohibited action.