Answer:
25%
Step-by-step explanation:
If a parent is heterozygous, it has 2 difterent alleles. Both parents are heterozygous for blood type A, so the genotype is AO. A masks the O because A is dominant over O, so A is the blood type.
Create a punnett square to find possible offspring
AA = Blood type A
AO = Blood type A
OO = Blood type O
There is 1 child out of 4 that have blood type O. So to find the percentage divide 1 and 4 and multiply by 100.
1÷4×100 = 25