Answer:
Frequency of the wave is f = 50 Hz
Step-by-step explanation:
It is given that, a wave oscillates 50 times per second. The number of oscillations per second is called frequency of a wave. Mathematically, it can be written as:

Here, number of oscillations, n = 50
So, frequency of this wave is equivalent to 50 Hz. It is equal to number of cycles per second.
So, the correct option is (b). Hence, this is the required solution.