Pcr is a useful technique because a. it makes enough copies to eliminate mutations b. it makes enough copies to study the dna c. it makes materials needed for unzipping the dna helix or d. it makes more copies than a restriction map does

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 : )