The nitrogen, oxygen, and other gases surrounding Earth A. are pulled toward Earth by gravity
B. are found mainly near the outer edge of the atmosphere
C. exert pressure only at sea level
D. exert pressure that works against atmospheric pressure

option A is correct

Explanation:

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.