Who are most likely to lie for serving purposes

A．Doctors are often in a dilemma as to tell the patient his real condition of health.
B．Doctors' reluctance to tell patient truth has no real support in reality.
C．Doctors' lies are different from that of lawyers and government officials.
D．Doctors and patients hold different views about telling truth.

A．a medical tradition
B．to harm their own integrity
C．to defend medicine
D．uttering the truth for truth's sake