Well you can know your limits. what you can and cant eat and how much your body can hold
The answer is B. Spine stretch
Spine stretch is an exercise to stretch your back bone, which mean your upper body, not the lower one.
NB :
Hip Flexor : To stretch your thigh
Calf stretch & Harmstring stretch : To stretch your lower legs
The microbiology department
I would say A because it sounds the most positive and sometimes people need a little push to get confidence to follow their dreams and be successful.