The correct option is A IAIO; Blood type A
Blood groups are inherited from our biological parents in the same way as eye colour and other genetic traits. Within the ABO blood group system, the A and B genes are co dominant, i.e., these will be expressed whenever the gene is present. The O gene is silent and only expressed when neither A nor B is present.
In the first marriage, the child is blood group O, IOIO which means both the parents have IO alleles. In the second marriage, the child has AB blood type. In this case, the father has B type, either IBIO or IBIB. This means the mother has A type blood with genotype IAIO.