Higher metabolic rates during growth and development periods such as puberty and pregnancy are part of
a. the body getting older.
b. the digestive process.
c. an increased need for rest.
d. rapid bodily changes.

phat

out of the choices i'd say d the ability to set goals, mainly because to desire to continue you need motivation but it isn't motivation in that part, but setting goals means you have an endgame and you want to reach it which sums up motivation.