Why did Mendel study pea plants?

Depending on the organism the number of in a cell may change

The response is the basis for vaccination. primary secondary tertiary none of the above

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population. b) the separated population is small, and genetic drift occurs. c) the isolated population is exposed to different selection pressures than the ancestral population. d) different mutations begin to distinguish the gene pools of the separated populations. e) gene flow between the two populations is extensive.