The father has a blood group 2, the mother has a 3 blood group. What blood type might their first child have?

The blood group is inherited according to the principle of multiple allelism, that is, the allele is represented by 3 genes A, B and O. Gene O is recessive in relation to A and B.
If the parents are homozygous: the father is AA (group 2), and the mother is BB (group 3) – their child can only have group 4 AB, since one gene is inherited from the father and the other from the mother.
If the parents are heterozygotes: the father is AO, and the mother is ВO, then the child can have any group: group 1 – OO, group 2 – AO, group 3 – ВO, and group 4 – AB, since the parents form gametes of 2 varieties.