Based on the cell theory, which of the following is true a
All living and nonliving things are made of cells.

b
All cells are too small to be seen with the naked eye.

c
Small organisms have smaller cells than large organisms.

d
Large organisms have more cells than small organisms.

b.All cells are too small to be seen with the naked eye.

Explanation:

the correct answer is:

a population changes in response to a change in the environment.

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.