The intracellular fluid (ICF) compartment is the system that includes all fluid enclosed in cells by their plasma membranes. Extracellular fluid (ECF) surrounds all cells in the body.
The genetic variation of organisms has three sources they are mutation, gene flow and sexual reproduction.
Explanation:
Genetic variation are caused by mutation , random mating, random fertilization and recombination between homologous chromosomes during meiosis.
It is a variation in alleles and genes, among the populations. There is a genetic variation within the family of closely- related individuals. If it is a neighborhood there are many families and there is also genetic variation among that group.
An exact genetic copy of the parent organism is produced in asexual reproduction. It only introduces the genetic variation into the population if a random mutation in the organism's DNA is passed on to the offspring.
B I believe humans were around at that time