If Kim Can Wash 10 Cars or Wax 2 Cars

If Kim can wash 10 cars or wax 2 cars during a day, and Susan can wash 8 cars or wax 2 cars during a day, then according to the law of comparative advantage,

A) Susan's opportunity cost of waxing a car is greater than Kim's.
B) their total output can be expanded if Susan specializes in waxing and Kim in washing.
C) their total output can be expanded if Susan specializes in washing and Kim in waxing.
D) it is impossible to expand total output through specialization and mutual exchange in this case.