Blood type is an example of codomiance because
A. The A, B and O alleles are all expressed equally.
B. the A and O alleles are expressed equally, but the B is recessibe to both.
C. The B and O alleles are expressed equaly, but A is recessive to both.
D. The A and B alleles are both expressed, but the O allele is recessive to both.
Answer: D