Which of these four processes prevents allopatric speciation from occurring?
a. genetic drift
b. gene flow
c. mutation
d. natural selection

Gene flow

Explanation: Allopatric speciation  is the situation of the occurrence of the barrier in the geographic region. Due to this factor the isolation of the population takes place. For the prevention of the allopatric speciation,gene flow stops that process . In this the gene flow is the flow of genes between the interbreeding population of a specific species. So speciation occurs only when there is no gene flow and effects the population.

answer; the above answer to the above statement is (true)