Mendel observed that the mutant alleles in his strains were always recessive. Why was this the case?
A. for the traits he studied, a copy of the wild type allele is enough to produce the wild type phenotype
B. for the traits he studied, the wild type alleles were haplosufficient
C. mutatnt alleles are always recessive
D. for the traits he studied, the wild type alleles were haploinsufficient
E. A and B are correct