The frequency of a simple pendulum that makes 120 complete oscillations in 3 minutes is:

0.67 Hz

Explanation:

Given that:

Number of oscillations = 120

Time taken for oscillations = 3 minutes

Since standard unit of time is seconds, convert 3 minutes to seconds

(If 1 minute = 60 seconds

3 minutes = 3 x 60 = 180 seconds)

Then, recall that frequency is the number of complete cycles or oscillations in one second, and its unit is Hertz.

Thus, frequency = (number of oscillations / time)

F = 120 / 180 seconds

F = 0.67 Hz

Thus, the frequency of a simple pendulum is 0.67Hz

d is the correct answer