Which of the following is a correct application of one of Darwin's postulates to the Galapagos finch data from Case Study #2?
A. All the birds, no matter their beak size, were equally likely to survive during the drought.
B. Variation in beak size was present in the population of finches prior to the start of the study.
C. Beak size is not a heritable trait.
D. All the birds, no matter their beak size, were likely to have the same number of offspring during the drought.