Amplitude is a measure of a waves a; speed b; distance c; energy d; frequency

Amplitude is a measure of distance of waves

Option B

Explanation:

Waves are usually represented in terms of frequency and amplitude. Amplitude refers to the distance or maximum displacement traveled by the waves in terms of time which is denoted by frequency.

Frequency can be defined as the number of cycles travelled per second whereas speed is the distance travelled by the wave per second. Hence distance is the right option from the other given options.