Answer:
a. 1/4 (because they are both heterozygotes)
Explanation:
A Punnett square two heterozygous (Gg) parents states that every child would have 1/4 chance of receiving the gg allele combination, resulting galactosemia .
Offsprings genotype probabilities are as follows :
1/4 GG (25%)
1/2 Gg (50%)
1/4 gg (50%)
        G       g
G Â Â Â Â Â | Â GG Â Â Â | Â Gg
g      |  Gg    |  gg