Help asap.

1. Why is the scrotum external on most male mammals?

A. serves as a climate-control mechanism of heating for the production of healthy sperm

B. allows air to circulate around this organ to help oxygenate the developing sperm

C. serves as a climate-control mechanism of cooling for the production of healthy sperm

D. allows for the cooler temperatures needed for the production of the hormones in a male mammal