A researcher grows a population of ferns in her laboratory. She notices, after a few generations, a new variant that has a distinct phenotype. When she tries to breed the original phenotype with the new one, no offspring are produced. When she breeds the new variants, however, offspring that look like the new variant result. What originally caused the change in the variant?
(A)Karyotyping (B)Balance polymorphism (C)Mutation (D)Polyploidy
C