Which process must first take place in order for the proteins in foods to be used by body cells?

(1) digestion (3) synthesis

(2) storage (4) excretion

Digestion

1 is correct since you need to eat something before anything else.

2 is incorrect since if this was first, what are you storing?

3 is incorrect since that is the second thing you need to do.

4 is incorrect since that is the last thing to do.