It is believed that mollusks evolved from .
A. Roundworms
B. None
C. Annelid worms
D. Arthropoda

None

Explanation:

Mollusks are cousins to Annelids. Both of those are distant evolutionary offshoots to flatworms. Roundworms are a separate species and arthropoda are animals with exoskeletons

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.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.