Question

mechanical waves are
forces start a disturbance, sending a wave through a material
waves that transfer energy through matter

Explanation:

Mechanical waves are waves that require a medium (matter) to transfer energy. The first option is a description of how a wave can be started (by forces causing a disturbance in a material), but the key defining characteristic of mechanical waves is their need for matter to transfer energy.

Answer:

Waves that transfer energy through matter