Question

3. Our tendency to feel wakeful and sleepy on a 24-hour basis depends mainly on

a. A cycle generated by a mechanism in the brain
b. Our perception of environmental stimuli such as heat and light
c. A cycle generated by hormone-producing organs such as the adrenal gland
d. Wear and tear on the muscles followed by a period of repair

I chose answer A. because humans have mechanisms that prepare for activity during the day and sleep at night. Is this correct?

Answer 1

Melissa -- none of your three posts have had anything but one number. If copying and pasting isn't working, you'll need to type your questions.