What phenomenon did Darwin observe in the
Galapagos island? What conclusion did he feel these
observations supported?

On his visit to the Galapagos Islands, Charles Darwin observed how birds specialize for different niches and the process of speciation - descent with modification. These observations supported his theory of evolution by natural selection.

Explanation:

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 : )

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.