Ace the North Carolina RADAR State Exam 2025 – Speed Your Way to Success!

The correct answer highlights that wavelength and frequency are characteristics of radio waves that can vary. In the context of electromagnetic waves, including radio waves, the speed of light is constant at approximately 299,792 kilometers per second in a vacuum. This means that as one characteristic changes, the other must adjust to maintain that constant speed.

According to the relationship between speed, frequency, and wavelength, the speed of a wave is equal to its frequency multiplied by its wavelength. Therefore, if the frequency increases, the wavelength must decrease to keep the product of frequency and wavelength constant (and vice versa). This relationship illustrates how wavelength and frequency are interdependent and variable in the context of radio waves.

The other options involve pairs of characteristics that either do not fully address the variable nature of radio waves or include speed, which is a constant in this context.