Darwin argued that the beak size and shape of Galapagos finch species was related to their
a. body size.
b. food source.
c. time of reproduction.
d. flight pattern.
Darwin argued that the beak size and shape of Galapagos finch species was related to their "food source", since those with the beaks that were most "fit" to catch the food in the area would pass the genes for these beaks along to their offspring.