Why does hydrogen bond so tightly to oxygen during cellular respiration? It is not electronegative, but oxygen is.
It is more electronegative than oxygen.
It is electronegative, but oxygen is not.
It is less electronegative than oxygen.

if your in connexus the answer is "it is less electronegative than oxygen"

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.