Suppose that we dislike this original sentence but can't easily find an objective error. In such a case, we can proceed to (B) and search for objective defects, noting that we have not decisively eliminated (A).
We might judge (B) less bad than (A). We'll come back to it. The verb tenses in (C) are unnecessarily involved -- in "was increasing" and "having become." So (C) is out. Choice (D) has the same problems and also a parallelism error -- a missing "because" after "as." Choice (E) also has a lack of parallelism between the phrase "because of," which introduces a noun, and "because," which introduces a clause. Indeed, that's also a problem with (A), between "because of" and the word "by."
The correct answer is (B).