C. Both are correct since sound waves are mechanical waves.
Explanation:
Both Sally and George are correct with their proposition. A mechanical wave can both be longitudinal or transverse wave. Sound waves are purely longitudinal waves.
A wave is a disturbance that transmits energy from one point to another.
Mechanical waves are waves that carries energy from one point to another through a medium.
Examples are sound waves. They can be longitudinal or transverse.
Longitudinal waves transfers energy parallel to their source.
Transverse waves are perpendicular to their sources.
