Why does the environmental protection agency establish emission guidelines for car exhaust?A)to maintain low air pollutions levels B)to maintain high air pressure levels C)to maintain consistent water supplies D)to maintain consistent cloud formations.

A.)

Explanation:

Hope this helps:)

D)to maintain consistent cloud formations.

Explanation:

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.

that scientist would be robert hooke