Question ID:PT20 S4 Q13 Passage:Mature white pines intercept almost all the sunlight that shines on them.  They leave a deep litter that dries readily, and they grow to prodigious height so that, even when there are large gaps in a stand of such trees, little light reaches the forest floor. For this reason white pines cannot regenerate in their own shade.  Thus, when in a dense forest a stand of trees consists of nothing but mature white pines, it is a fair bet that _______. Stem:Which one of the following most logically concludes the argument? Correct Answer Choice:AChoice A:the ages of the trees in the stand do not differ from each other by much more than the length of time it takes a white pine to grow to maturity Choice B:the land on which the stand is now growing had been cleared of all trees at the time when the first of the white pines started growing Choice C:competition among the trees in the stand for sunlight will soon result in some trees' dying and the stand thus becoming thinner Choice D:other species of trees will soon begin to colonize the stand, eventually replacing all of the white pines Choice E:any differences in the heights of the trees in the stand are attributable solely to differences in the ages of the trees