In Tim Birkhead's Study of Zebra Finches, Male Birds Fed

Multiple Choice

In Tim Birkhead's study of zebra finches, male birds fed water with added carotenoids

A) had much brighter bills than control males had.
B) were preferred by females.
C) developed thicker skins than control males did.
D) had stronger immune systems than control males had.
E) All of the above