Which statement is true?
A. Light waves always travel at a constant speed, but sound waves do not.
B. Waves travel at different speeds through different materials.
C. Light waves and sound waves travel at the same constant speed.
D. Wave speed depends on the amplitude of the wave.

Where do most of the visible electromagnetic waves on Earth come from?
A. X-rays
B. radio waves
C. the sun
D. fluorescent lights

Yellow light and blue light are two examples of electromagnetic radiation from the sun. Which statement correctly compares yellow light and blue light?
A. They have the same wavelength.
B. They are both types of ultraviolet light.
C. They are both types of visible light.
D. They travel at different speeds.