[单项选择]

The field of medicine has always attracted its share of quacks and charlatans—disreputable women and men with little or no medical knowledge who promise quick cures at cheap prices. The reasons why quackery thrives even in modem times are easy to find.
To begin with, pain seems to be a chronic human condition. A person whose body or mind hurts will often pay any amount of money for the promise of relief. Second, even the best medical treatment cannot cure all the ills that beset men and women. People who mistrust or dislike the truths that their physicians tell them often turn to more sympathetic ears.
Many people lack the training necessary to evaluate medical claims. Given the choice between (a) a reputable physician who says a cure for cancer will be long, expensive and may not work at all, and (b) a salesperson who says that several bottles of a secret formula "snake oil" will cure not only cancer but tuberculosis as well, some individuals will
A. has a special ability
B. has little knowledge
C. is not a good doctor
D. pretends to be a doctor