Which term completes the following sentence: Electromagnetic radiation includes waves of many different ____________?

• A. Frequencies
• B. Wavelengths
• C. Energies
• D. Amplitudes

Answer: (A)

The main idea here is that electromagnetic radiation comes in a broad range of tones that differ in how often the wave oscillates each second. That rate, called frequency, is the direct way we describe and compare different kinds of light—from radio waves to gamma rays. Because the energy of a single photon is proportional to its frequency (E = hf), higher-frequency waves carry more energy, which is a central reason frequency is the most fundamental descriptor in this context. While wavelength and frequency are related (through the constant speed of light), the sentence emphasizes the variety in how often the waves occur, making frequencies the best fit. Amplitude describes how strong the wave is, not the diversity of the waves, and energies are tied to frequency rather than being a separate varied label in the same sense.