Are chemicals internal or external?

it depends

Explanation:internal chemicals are when we are talking about the human body or any living organism. external chemicals would be like a mixture or atmosphere type stuff, Does the make sense???

eukarya because is is like alche and b is bacteria and d is animals

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.