Answer: A. Does the wave require a medium to travel.
Step-by-step explanation:
Mechanical waves require the presence of a material object to be able to engage in energy transfer. For example, Sound is a mechanical wave that needs a medium to travel such as a solid or liquid.
Electromagnetic waves on the other hand, are able to travel through a Vacuum including that of space and they include all light waves. This is why the sun's light is capable of reaching Earth.