Which scenario causes gene flow?
A. new mutations arise within populations
B. an animal moves to a new population and mates
C. one flower pollinates other flowers in its population
D. a population's size decreases after a natrual disaster
A. new mutations arise within populations
B. an animal moves to a new population and mates
C. one flower pollinates other flowers in its population
D. a population's size decreases after a natrual disaster