The bottleneck effect is used to describe an event where a population decreases. one example involves the northern elephant seal. they have a reduced genetic variation due to a population bottleneck humans inflicted on them in the 1890s. hunting reduced their population size to as few as 20 individuals at the end of the 19th century. their population has since rebounded to over 30,000, but they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted. what of these would best define this change if gene frequency?
a) gene flow b) speciation c) genetic drift d) natural selection

The correct answer would be C)genetic drift.

Genetic drift is defined as the change in the relative frequency of alleles in a population as a result of a sudden decrease in the population size.

Events like natural disaster, excessive hunting et cetera can drastically reduce the population size in a very short period of time.

It results in the loss of many alleles and thus the genetic variation of the population gets lost.

Similarly, hunting reduced the population of northern elephant seals to as low as 20 individuals due to which most of the genetic diversity of the population was lost.

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 : )