A population ecologist observes that the surface area of leaves in a species of dandelion growing in a desert is much smaller compared to the larger surface area of leaves of the same species growing in areas that receive greater rainfall. She gathers seeds from individual plants growing at both low and high rainfall locations, plants them in a uniform environment in a greenhouse, and measures the leaf area of the new plants. All of her experimentally grown plants grow to have similar leaf surface areas. From this she concludes that _____.
a. leaf surface area is not an adaptive trait that promotes fitness
b. the variation she originally observed was due to genetic differences
c. the variation she originally observed was due to disruptive selection
d. the variation she originally observed was an example of non-genetic environmental influence
e. stabilizing selection was responsible for leaf-area differences in the parent plants