OG12-19 求助选项B的OG解释为何

OG12-19

Physician：The hormone melatonin has shown promise as a medication for sleep disorders when taken in synthesized form. Because the long-term side effects of synthetic melatonin are unknown, however, I cannot recommend its use at this time.

Patient：Your position is inconsistent with your usual practice. You prescribe many medications that you know have serious side effects, so concern about side effects cannot be the real reason you will not prescribe melatonin.

The patient's argument is flawed because it fails to consider that

A) the side effects of synthetic melatonin might be different from those of naturally produced melatonin

B) it is possible that the physician does not believe that melatonin has been conclusively shown to be effective

C) sleep disorders, if left untreated, might lead to serious medical complications

D) the side effects of a medication can take some time to manifest themselves

E) known risks can be weighed against known benefits, but unkonwn risks cannot

The explanation in OG

B) It is quite reasonable for the patient's argument not to mention this possiblity, especially since the physician expresses a belief that synthetic melatonin may be effective—but expresses no belief about whether or not it has been conclusively shown to be effective

Don't know how it explains that B does not indicate the flaw in the patient's argument.