Hi, our job here is not to strengthen the conclusion per se, but to find the answer that the author necessarily has to agree with for their argument to work. The author doesn't have to agree with A, in fact it's perfectly possible the author thinks that future efforts are a good idea and that researchers have been focusing on the wrong things. However they must agree with B, since if B were incorrect, then the issue wouldn't be the failure to develop new strains but rather some other cause of the decline.
