Bell and collaborators painstakingly documented a population of fossil sticklebacks from an ancient freshwater lake over a 20,000-year period. The prevalence of sticklebacks with full and reduced pelvises changed over time. Which is trueA. Initially (time A), fish with full pelvises (red line) were most common in the lake population.
B. At time B, the frequency of fish with full pelvises was very high. At time C, this population started to evolve reduced pelvises.
C. In this population, having pelvic spines seems to have provided a selective advantage to stickleback fish beginning at time C.
D. The evolution of pelvic reduction seen in this fossil record is different from the phenomenon occurring in the lakes of Alaska today.