Answer:
hello your question lacks the required options hence I will give you a general answer
answer : gg ( gray fly ) * Gg ( heterozygous black fly )
Explanation:
Let black body ( G ) be the dominant allele to gray body ( g )
hence the possible combination that will represent a parental cross when a gray fly is crossed with a heterozygous Black fly will be
gg ( gray fly ) * Gg ( heterozygous black fly )
