Evolution of a new trait typically takes many generations. Yet a dramatic shift in the extent of armor plating the the lake Washinton stickleback population occurred in the 50 years following the cleanup of the lake. Which of the following best describes the mechanism of t he rapid evolution of the armor phenotyp in the lake Washinton sticklebacks?

a. Pollutants in lake washinton forced the sticklebacks to increase their mutation rate

b. The rapic change in the lake Washington ecosystem required individual sticklebacks to evolve complete armor quickly

c. The increase in visibility in lake Washington allowed sticklebacks to visually select mates with low armor.

d. new selective pressures favored individuals with the plated phentotype, causing the plated allele frequency in the population to quickly increase.