Explanation

Creating a filter: In this question, the sentence needs "whether," not "if." Here exact English differs from common English. If it's a yes or no question expressed by a clause, the proper word is always "whether." The word "if" has a different function, which is to identify a condition for something. A simple test is to use "or not" -- if "or not" fits in the sentence, then the right word is "whether." I.e., "the construction of a new pipeline depends on whether or not it will exacerbate the problem..." makes sense, so the word must be "whether."

Applying the filter: the filter leaves us with (B) and (C). Choice (C) has multiple errors. The phrase "it is likely" is unnecessary and "will have" is not parallel or consistent with "likely to exacerbate." (D) and (E) are wordy and imprecise. "How likely" would be a viable option here, but it doesn't appear. The correct answer is (B).