For diffusion to occur, which condition must be met

A concentration gradient must exist. hope this helps

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )

a chain link fence because there so tiny even my albino donkey can't get out