In this question, they are telling us that the parents have AB blood type.
The blood type gene has 3 alleles: Iᵃ, Iᵇ, and i. Iᵃ codifies for the production of the antigen A on the surface of red blood cells, Iᵇ produces antigen B and i don't produce any antigen.
Iᵃ and Iᵇ are codominant to each other and dominant over the allele i.
Someone with AB blood type has a copy of the allele Iᵃ and other of the allele Iᵇ, and it has both antigens A and B on the surface of red blood cells.
So, let's look at the Punnett square of the crossing of two people with AB blood type, and a IᵃIᵇ genotype.
As we can see in the Punnett square, the child could have the genotypes IᵃIᵃ, IᵃIᵇ, or IᵇIᵇ, which means blood type A, B, and AB, respectively (options I, II, and III).
This means the right answer would be C. I, II, and III