According to "life without gravity," why can astronauts' muscles become weak?
a. without gravity, the blood is rerouted from the legs to the head.
b. without gravity, the body "grows" by as much as several inches.
c. without gravity, eating is difficult, so the body does not get proper nutrition.
d. without gravity, the muscles do not need to do as much work.

The correct answer is A

Explanation:

This because in space there is microgravity I.e absence or less gravity, the astronaut do not need to do much work, just to sleep, eat and go around. In microgravity the muscles are prone to atropy( respons e to gravity) which causes the muscle to be stiffen and straighten out, the muscles becomes weak.

the answer is d p: cell, q: organ, r: organ system, s: tissue