Which statement correctly describes a key difference between a radio wave and a sound wave?

• A. A radio wave requires a material medium to propagate, whereas a sound wave can travel through vacuum.
• B. Radio waves are longitudinal waves in air, whereas sound waves are transverse waves in vacuum.
• C. A radio wave is an electromagnetic wave that can travel through vacuum, whereas a sound wave is a mechanical pressure wave that requires a material medium.
• D. Both radio waves and sound waves are electromagnetic waves, but radio waves have higher frequencies.

Answer: (C)