It was important that Mendel examined not just the F1 generation in his pea breeding experiments, but the F2 generation as well, because
A) he obtained very few F1 progeny, making statistical analysis difficult
B) parental traits that were not observed in the F1 reappeared in the F2, suggesting that the traits did not truly disappear in the F1
C) analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment
D) the dominant phenotypes were visible in the F2 generation but not in the F1
E) he ate all the peas from the F2 generation so he couldn't collect data from them