Ascientist studied four fossils of a marine mammal dating back to 50 million years, 45 million years, 40 million years, and 30 million years ago. which fossil is most similar to the present-day mammal?

30 million years is your answer hope this helps

the answer is b.) hydrogen bonds between bases.

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 : )