At one's behest means because of someone's request or order. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• The meeting was arranged at the director's behest.
• In an HSC essay, At one's behest can express this meaning: because of someone's request or order.
• When this expression appears in a passage, connect At one's behest with the idea of because of someone's request or order.