Why B not A?

@DavidClimber, The argument is about breeding, not races. The veterinarian is arguing against a claim that "horses with this defect should not be bred" and concludes that such horses are in great demand in the horse show industry. He never expresses his opinion on whether such horses should be allowed to race. (B) accurately reflects the veterinarian's opinion. Let me know if you have any further questions.

Neither the passage nor the question stem refer to an absolute ban. How are we to determine that the breeders conclusion would result in an absolute ban, making B the correct answer?

Absolute ban does seem problematic but it really doesn't contradict what horse breeders want which is that horses with this genetic disease should not be bred. Compared to the only other answer that could be considered E , E goes way to far and includes all diseases which is way too broad than what the argument is about. B isn't worded perfect but is far better than E

Just chiming in to echo the last point made. While absolute bad does seem to be slightly stronger than the stimulus (should not be bred) this is actually not a major issue for this question. Stating that something should not be allowed to happen is very close to supporting banning it absolutely. A small difference in magnitude is ok for a main point question, as the correct answer will be a paraphrase of the conclusion of the stimulus.