Blood entering the lungs exchanges A. Oxygen for nitrogen
B. Carbon dioxide for oxygen
C. Nitrogen for oxygen

i don’t no. suiopgohjk

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

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.

meiosis is the first to occur after the nuclei of opposite of opposite mating types fuse