Bunuel wrote:
During the day in Lake Constance, the zooplankton D. hyaline departs for the depths where food is scarce and the water cold. D. galeata remains near the warm surface where food is abundant. Even though D. galeata grows and reproduces much faster, its population is often outnumbered by D. hyaline.
Which of the following, if true, most helps to resolve the apparent paradox?
A. The number of species of zooplankton living at the bottom of the lake is twice that of species living at the surface.
B. Predators of zooplankton, such as whitefish and perch, live and feed near the surface of the lake during the day.
C. In order to make the most of scarce food resources, D.hyaline matures more slowly than D. galeata.
D. D. galeata clusters under vegetation during the hottest part of the day to avoid the Sun’s rays.
E. D. galeata produces twice as many offspring per individual in any given period of time as does D. hyaline.
OFFICIAL EXPLANATION
The presence of predators of zooplankton, feeding near the surface during the day, would suggest that D. galeata is consumed at a higher rate than D. hyaline. Therefore, if this choice were true, it would help resolve the apparent paradox that D. galeata grows and reproduces faster than D. hyaline, yet D. hyalian has the greater population.
A is incorrect. Nothing is said in the paragraph to show the relevance of the presence of other species of zooplankton to the relative population size of the two species. C is not correct. This information explains the slower growth and reproduction of D. hyaline, which is one aspect of the paradox; but it does nothing to show how D. hyaline can grow and reproduce more slowly and yet have the greater population. D is incorrect. Nothing is said in the paragraph to show the relevance to the paradox of D. galeata’s clustering under vegetation. E is also incorrect. More information on the faster reproduction of D. galeata does not show how, despite faster growth and reproduction, D. galeata has the lesser population.