Reservoir . This is the correct answer trust me .
Here are the four postulates of natural selection, according to Charles Darwin:
1. variability - refers to different mutations that create different species
2. heritability - refers to the genes that are passed from one organism onto its descendants
3. overproduction of offspring - refers to the fact that more "children" is born than dies
4. natural selection - refers to those organisms that survive because they adapt to their surroundings better than those who will die
there are two distinctions of genders in humans, one is biological and the other is socially constructed.
biologically, man and women are distinguish by the gonads, such are men posses Penis and and women have Vaginas. secondly, through penis men produces sperm which is necessary for fertilization, while women have ovum which is serves as the carrier of sperm and produces a new young ones after , sperm meets egg.
socially men and women are constructed as men are to face the social world while women have to care for the family and house.