Concept:Mechanical waves require a material medium, and longitudinal waves have particle vibrations parallel to the direction of wave travel.
Explanation:Sound waves are mechanical because they need a medium such as air, water, or solid material to travel through.
They are also longitudinal because the particles of the medium vibrate back and forth along the same line as the wave moves.
Water waves are mechanical but not purely longitudinal; they combine transverse and longitudinal motion.
Seismic waves are mechanical but include both longitudinal and transverse types.
Light waves are electromagnetic and transverse, not mechanical.
Therefore, the only wave that is both mechanical and longitudinal is the sound wave.
Answer:Sound waves (Option C).