GMAT Sentence Correction (SC) | Re: Maine will face a serious shortage of timber by the year

Maine will face a serious shortage of timber by the year 2000, the result of a major infestation of spruce budworm,that much of Maine's spruce and fir forests are coming to maturity , and a rapid expansion of the paper business.

(A) that much of Maine's spruce and fir forests are coming to maturity
(B) that coming to maturity of much of Maine's spruce and fir forests
(C) much of Maine's spruce and fir forests are coming to maturity
(D) Maine's spruce and fir forests, much of which is coming