Explain why energy does not always appear to be conserved in some energy transfers and transformations. Use evidence from the Rube Goldberg

think its the third option

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.

option number c is the right answer.