Why does sperm development occur in an external structure of the body?
to give sperm easier access to the urethra
to allow easier blood flow
to manage sperm's temperature
to keep it separate from the rest of the body
DONE

To manage sperm's temperature.

Explanation:

Because the testicles can move depending on heat. They come closer to the body in the cold, farther out in heat.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.