The correct answer is B) Repeat your signal. When you have sent a visual signal to an aircraft, and the aircraft then flies over your position on a straight course and level altitude, the proper action is to repeat your signal. This allows the aircraft to confirm your location and the nature of your distress or need for assistance. Repeating the signal ensures the aircraft crew has received and understood your initial transmission. The other options are not correct: A) sending additional signals is unnecessary, C) preparing for a helicopter pickup is premature, and D) changing course to follow the airplane would be the wrong action in this scenario.