What is true of sand dunes? A) they are built by waves B) they are made by rivers cutting through land C) they are built by water carrying sediment away D) they are built by deposition of sand by wing.

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.

c is the answer to this question. altitude affects the weather because air molecules evaporate.