During puberty your heart almost: A. doubles in size
B. shrinks in size
C. Triples in size

Because without physical activity, the body has extra "energy" if you will, and so when it is time for bed you are not tired, so you end up staying up all night. also there is probably an effect on your internal clock, which messes with your melatonin production which goes hand in hand with your sleep cycle

Ithink the answer is talking about their problems  

The fetus at this stage is curled up, almost doubled over, so remember to consider this as you draw the fetus the correct length