What did chloroplasts evolve from according to the endosymbiotic hypothesis?
a. ribosomes
b. mitochondria
c. aerobic bacteria
d. photosynthetic

your answer is "the 1950's"

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 : )