How were the Galapagos finches important for Darwin's research?
a. He found that differences in beak shape showed selection on traits that are usefulin specticenwisen
b. He realized that the variation in finch beaks was something he could not explain.
c. He observed that unattractive finches died and could not reproduce.
d. He found that finches had many varieties of beaks no matter what island he went to.