Part a in a disputed parentage case, the child is blood type o, while the mother is blood type

a. what are the possible blood type (s) for the father

Child type o = > genotype oo

mother type A = > genotype AA or Ao

AA would not have given birth to type o (genotype oo), mother must have genotype Ao.

So father must contribute to the other o allele, so possible genotypes are:

Ao, Bo or oo.

Therefore the father's possible phenotypes are type A, type B or type O.