A mother with a blood type of A has a son with a blood type of B. Which of the following are possible? Select all that apply
A. the mother is homozygous for blood type.
B. The mother is heterozygous for blood type
C. the father is homozygous for blood type.
D. the father is heterozygous for blood type
E. the father has type A blood
F. the father has type O blood