Thanks for the question! The problem with (A) is that we don't have support for the fact that Barite is "the most environmentally damaging" ingredient of drilling muds. We are told that barite is environmentally damaging in passage B, but not that it is the most environmentally damaging of the drilling mud ingredients. Passage A doesn't mention the environmental ramifications of barite. Since the question requires that we can reasonably infer the answer from the two passages, (A) is wrong. Hope this helps!