What would be the outcome of crossing two strains of wingless flies that belong to the same complementation group?

Wingless offspring

Explanation:

Complementation is the terminology used for finding difference in the mutation of same or different gene.

Two groups with same complementation have failed to complement each other.

Thus, two wingless flies will have the same genotype i. e "ww"

When two wingless flies are crossed following offspring are produced

ww * ww

ww, ww, ww, ww

All the offspring are wingless too