After Reading the Paragraph Below, Answer the Question That Follows

Multiple Choice

After reading the paragraph below, answer the question that follows.
A stonefly is an aquatic insect that has an incomplete life cycle. It spends its growing period (nymph life stage) on the bottom of streams, camouflaged by the rocky bottom. When it has finished growing, it crawls to the edges of streambeds to molt and emerges as a winged adult. Fish often eat the juvenile nymphs as they make their way to the edge of the streambeds.
-Suppose that scientists who study predator-prey relationships notice that over a 50-year span, new color patterns evolve in the stonefly nymphs such that they are better able to blend into the colors of a streambed. What would be a logical and reasonable question that the scientists could investigate in relation to their observations and their knowledge of predator-prey relationships?

A) As the color pattern changes in nymphs developed, was there also a change in the color of the sand of the streambeds on which the nymphs molted?
B) As the color pattern changes in nymphs developed, was there an increase in the fish population size?
C) As the color pattern changes in nymphs developed, was there a decrease in the phosphorus concentration in the stream water?
D) As the color pattern changes in nymphs developed, did the fish eat a greater number of nymphs?