A boy observes a robin outside of his window. He notices the robin repeatedly cocks its head to one side before pecking the ground. The boy suspects that when the robin cocks its head it is actually listening for worms or insects underground. How could the boy test his hypothesis about robins and worms?

A)He could count how many times a single robin catches a worm after it cocks its head and pecks the ground.
B)He could catch a robin and place it in an enclosure without worms or insects, and observe whether the robin still cocks its head.
C)He could observe several robins, and see if they all exhibit the same head-cocking and worm-catching behavior.
D)All of these experiments would test the boy's hypothesis.