Which of the following has the highest velocity ?

Light is the correct answer. In vacuum, light travels at c, about 3 × 10⁸ m/s, and no material particle or disturbance can exceed this under special relativity.

• Cosmic rays: Most are high-energy protons. They can travel at speeds very close to c, but as massive particles they can never reach it, because the energy needed grows without limit.
• Electron: It has rest mass, so the same logic applies. Accelerators push electrons extremely close to c, but never to c.
• Supersonic wave: Any speed above the local speed of sound qualifies, which is about 340 m/s in air. That is roughly a millionth of c, so it is far slower.

The core concept is the speed of light as the universal speed limit, which links mass, energy and relativity. This is a Modern Physics point that also matters for Mains answers on science and technology.

Trap: Aspirants sometimes pick light because it slows in water or glass. The comparison here is for vacuum, so the reference value is c.