Not really sure about this one can someone plz?

The answer is probably B

before we can answer, we have to see the choices that are printed there with the question.   that's the only way we can point you to the correct one.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.