36.Two decades after the river dam was built, none of the eight fish species native to the river was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.
Which of the following most strengthen the scientists' hypothesis?
A.The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains 50 degrees.
D.The lowest recorded temperature of the river before the dam was built was 34 degrees,whereas the lowest recorded temperature of the river after the dam was built has been 43 degrees.
科学家认为温度的rising导致繁殖问题，那么D不正是讲的rising吗？不就加强科学家的推理吗？
答案却是A。。。。。why why why??anyone can tell me?
thanks! | 
