If a father with A-type blood and a mother with B-type blood have a child, what is the probability that the child will have O-type blood?

A. 50 % chance if both parents have the recessive allele.
B. 25 % chance if both parents have the recessive allele.
C. 0 % chance because neither parent has the allele.
D. 50 % chance if either parent has the recessive allele.

B

Two teachers expressed concern over this question arguing that both B and C could be correct. It is agreed that ruling out answer C is based on the subtleties of language as the data does not support the statement that definitively neither parent has the allele. C would only be correct if the statement said "if neither parent has the allele".