This motion may be approximated by that of the tines of a tuning fork when struck, and could be seen as a sinusoidal or SINE WAVE from the trace of a pen attached to the tine and moving against paper ...

Traditionally, the introductory view of the pendulum is to show that for small amplitudes the motion of the mass is like a simple harmonic motion (motion of a mass on a spring) with a period of ...

Hence, the correct option is (d).

Simple harmonic motion is introduced with a discussion of spring force and spring potential energy and how that motion relates to waves.

Then the events repeat. And that's simple harmonic motion. There will be a furious few commenters already writing about damping and vectors and Taylor expansions of potential wells and my complete ...