A doctor is a very important person. He works very hard. The doctor gives medicine to sick people. He wears a white coat. A stethoscope hangs around the doctor's neck. He uses it to listen to the heartbeat of the sick people. The doctor works in clinics and hospitals. His job is very difficult.A doctor treats _______ people.

• A. healthy            
• B. fit
• C. sick
• D. Both [a] and [b]
• E. None of these