Energy is directly proportional toSelect an answerAwavelengthBfrequencyCamplitudeDnone of these

The energy of a wave is directly proportional to its frequency. Therefore, the correct answer is Bfrequency.

Here's a step-by-step explanation:

1. The energy of a wave is determined by its frequency, not its wavelength or amplitude. This is based on the Planck-Einstein relation, which states that the energy of a photon (a particle of light) is equal to its frequency multiplied by Planck's constant.

2. Frequency is the number of wave cycles that pass a given point per unit of time. The higher the frequency, the more energy the wave carries.

3. Wavelength is the distance between one wave cycle and the next, and amplitude is the height of the wave. While these properties can affect how we perceive the wave (for example, wavelength affects color and amplitude affects brightness in light waves), they do not directly determine the wave's energy.

4. Therefore, the statement "Energy is directly proportional to frequency" is correct, and the answer to your question is Bfrequency.