The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and
A) their chromosomes are no longer homologous enough to permit meiosis.
B) a constant number of viable, fertile hybrids is produced over the course of generations.
C) the hybrid zone is inhospitable to hybrid survival.
D) an increasing number of viable, fertile hybrids is produced over the course of generations.
E) a decreasing number of viable, fertile hybrids is produced over the course of generations.
