The Function of a Single Fruit Fly Gene Was Inactivated

Multiple Choice

The function of a single fruit fly gene was inactivated completely by mutation.A fruit fly with this mutation did not have legs.Which is a reasonable conclusion to make based on this information?

A) The normal gene function is required for viability in fruit flies.
B) The normal gene function is required for leg formation in fruit flies.
C) The normal gene is unlikely to regulate other genes involved in leg formation.
D) The normal gene is likely required in fruit flies for formation of legs, wings, and antenna.