Electromagnetic waves require no medium and travel at light speed

Steps:

• Define electromagnetic spectrum: waves from oscillating electric and magnetic fields, including radio, microwave, infrared, visible, UV, X-ray, gamma.
• Classify options: radio waves (A) and TV signals (B) are low-frequency EM waves; UV (D) is high-frequency EM; ultrasound (C) is sound.
• Confirm ultrasound as mechanical longitudinal waves needing a medium, unlike EM waves.
• Select non-EM option based on propagation and nature.

Why C is correct:

• Ultrasound consists of mechanical pressure waves in matter, per wave mechanics, not electromagnetic fields (Maxwell's equations).

Why the others are wrong:

• A: Radio waves are long-wavelength EM radiation used for broadcasting.
• B: Television signals are modulated radio waves, part of the EM spectrum.
• D: Ultraviolet waves are short-wavelength EM radiation beyond visible light.

Final answer: C