Answer: Option B.
Geographic separation.
Explanation:
It is geographic separation that is common to both of them because
Sympatric speciation to occur when certain populations of species isolate reproductively from the the main populations because they can not longer interbreed with each other and they inhabit the same geographical location.
Allopatric speciation occur when two populations of the same species separate from each other geographically which can be as a result of one group of population move to another geographical location.
