Which best describes darwin’s studies that led to the theory of evolution?
a) extensive research of an individual organism within a short period
b) extensive research of an individual organism over many years
c) observations and data collected within a short period
d) observations and data collected over many years

D)

Explanation:

d

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.