When a person sitting on a swing stands up on the swing, the frequency of oscillation

Answer: Option B

In Simple Harmonic Motion, the frequency of the oscillation (f) is the number of oscillations per second which is expressed as
f = 1 / T
where T is the time period (the time for the oscillator to complete one cycle). Now, when a person sitting on a swing stands up on the swing, the effective length of the swing decreases. When length decreases, the time period also decreases. Since frequency of oscillation is inversely proportion to time period, it increases in the present case of man standing up on the swing.