12. Natural selection varies the shape of the beaks amongDarwin's finches in response to the available food supply.
B. to the available nest building material supplies.
c. to the availability of potentialmating partners.
D. to presence of ectopara sites on their feathers.
Е. to the need to improve their feather preening abilities.

Adaptive radiations can be a direct consequence of four of the following five factors. selectthe exception. a) vacant ecological niches b) genetic drift c) colonization of an isolated region that contains suitable habitat and few competitor species d) evolutionary innovation e) an adaptive radiation in a group of organisms (such as plants) that another group uses as food