The picture represents a structure of the respiratory system. Alveoli in the lungs.

Which is the function of this structure?

to bring air into the body

to exchange oxygen with carbon dioxide

to carry air to the lungs

to release oxygen from the body

20 pts available

B. To exchange oxygen with carbon dioxide.

Explanation:

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B; to exchange oxygen with carbon dioxide

Explanation:

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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.