D. Wash his hands in the handwashing sink. Is the correct answer, because it cleans all germs of your hands.
A. Is not the answer because hand sanitizer doesn't really clean your hands.
B. Is not the answer because a clean towel doesn't clean your hands.
C. Is not the answer because a santizing solution cleans your hands but doesn't get all the germs off.
Hopefully this helps you, have a good day.
