In this image, which blue letters represent polar covalent bonds. select them by going by the blue letters.

The answer to your question is  A, C, and F

Explanation:

Polar covalent bonds are formed between two nonmetals which difference of electronegativity is between 0.5 and 1.7. Use this rule to determine which bonds are polar covalent bonds.

A)  H and O     3.44 - 2.2 = 1.24           Polar covalent bond

B)  C and H      2.55 - 2.2 = 0.35        

C)  C and O      3.44 - 2.55 = 0.87        Polar covalent bond

D)  C and C      2.55 - 2.55 = 0

E)  N and C      3.04 - 2.55 = 0.49      

F)  N and H      3.04 - 2.2 = 0.84          Polar covalent bond

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.