in this forest, trees block much of the sunlight from reaching the ground. the branches of trees grow up and out to reach as much sunlight as they can. which challenge of life does this example represent? a) obtaining energy b) needing sleep c) reproducing d) maintaining structure

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.