The correct option is A 0.02 s
The way our brain interprets the frequency of a sound is called the pitch. The faster the vibration of the source, the higher is the frequency and the higher is the pitch.
We know frequency, f=1Time period.
Among the given waves, the wave with a time period of 0.02 s has the least time period.
Therefore, from the above equation, we can say that it has the maximum frequency i.e. 10.02=50 Hz.
Since pitch is directly proportional to frequency, the wave with a time period of 0.02 s has the maximum pitch among the given.