+ A certain chemosynthetic bacterium produces glucose via the following reaction.
6 H2S
6 CO2
6 02 6 H20
hydrogen sulfide carbon dioxide
oxygen water

the answer to your question is:

c. complementary base-pairing

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.