A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds.

Which of the following statements might best explain the increase in average beak size in the finch population during the drought?

A. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.
B. Finches with bigger beaks can attack and kill finches with smaller beaks.
C. Finches with bigger beaks possess more powerful flight muscles and are able to find more food.
D. Finches that crack large seeds develop larger beaks over time.