In a Field Experiment, a Man Who Did Not Need

In a field experiment, a man who did not need dental treatment consulted 180 dentists. 50 dentists recommended at least one filling. Explain the moral hazard.

A) The "patient" was less well informed about his condition than the dentists.
B) The 50 dentists exploited his ignorance to recommend treatment that was unnecessary but would increase their earnings.
C) Both a and b.
D) Neither a nor b.