Final answer:
A light bulb generates electromagnetic waves that can travel through a vacuum, unlike mechanical waves from a speaker, earthquake, or volcanic eruption, which require a medium.
Step-by-step explanation:
Among the options provided, the one that generates waves capable of traveling through a vacuum is a light bulb. A light bulb emits light, which consists of electromagnetic waves. Unlike sound waves from a speaker or waves from earthquake activity and volcanic eruptions, which are mechanical waves requiring a medium like air, water, or solid materials to travel through, electromagnetic waves do not require a medium. They can propagate through the vacuum of space, which is why we can see the light from stars and other celestial objects millions of miles away.