Rhonda has gained fifteen pounds since she started a sedentary part-time job and began eating fast food more frequently. her weight gain is likely due to factors. \

She probably is gaining more weight due to the fact that she is busy working a lot and she is not having the best eating habits.

(a) is not correct because one does not get increased cholesterol  from lifting weights.(b) is not correct because lifting weights cannot reduce the risk of a hereditary disease.(c) is not correct because back pain isn't a benefit! and plus, if he lifts weights properly, he should not have back pain.(d) is the correct answer because his ligaments will gain mass, making it easier for him to carry heavier weights and he will also be stronger!