Officers Have Stopped a Motorist and Recognize Him from a Previous

Officers have stopped a motorist and recognize him from a previous drug arrest. They ask and he consents to a search of the car. Just as an officer is about to reach under the passenger seat the suspect says, "Stop. I've changed my mind. No more search." Given the circumstance, what legal course of action do the officers' have?

A) now have probable cause and may continue the search.
B) must stop the search and let the driver go but may impound the car.
C) may arrest the driver and justify the search under Belton.
D) must stop the search and not use the withdrawal of consent as an excuse to detain him further.