Wirth: All efforts to identify a gene responsible for predisposing peo

Wirth: All efforts to identify a gene responsible for predisposing people to manic-depression have failed. In fact, nearly all researchers now agree that there is no “manic-depression gene.” Therefore, if these researchers are right, any claim that some people are genetically predisposed to manic-depression is simply false.

Chang: I do not dispute your evidence, but I take issue with your conclusion. Many of the researchers you refer to have found evidence that a set of several genes is involved and that complex interactions among these genes produce a predisposition to manic-depression.

The point at issue between Wirth and Chang is whether


(A) efforts to identify a gene or set of several genes responsible for predisposing people to manic-depression have all failed

(B) it is likely that researchers will ever be able to find a single gene that predisposes people to manic-depression

(C) nearly all researchers now agree that there is no manic-depression gene

(D) current research supports the claim that no one is genetically predisposed to manic-depression

(E) the efforts made to find a gene that can produce a predisposition to manic-depression were thorough


The answer is, IMO, B.

The discussion is based on whether there is a gene for a certain disease, manic-depression. Both Wirth and Chang agreed the evidence but Chang disagreed Wirth with his/her conclusion that a claim that some people are genetically predisposed to manic-depression is simply false.
B is correctly stating that there is a possibility of finding a gene to prove Wirth's claim wrong.
All other choices are actually saying that there is no possibility.