Answer:
Father - AO
Mother - AO
Baby - OO
Explanation:
This question involves blood type in humans where blood types A and B are dominant over blood type O, but A and B codominant. In this blood group system:
- Genotypes AA and AO are phenotypically type A
- Genotypes BB and BO are type B
- Genotype AB is type AB
- Genotype OO is type O
According to this question, a man with type A blood marries a woman with type A blood. They have their first child as type O blood. This means that both parents of this child are heterozygous type A i.e. AO and AO. This is the only way the parents can have a child with type O (genotype OO). Hence,
Father - AO
Mother - AO
Baby - OO