amplitude of an oscillation

Question

This is the same situation: a thingy oscillating on the end of a spring. The system is set vibrating by pulling the thingy down below its equilibrium position and then letting it go from rest

The amplitude of the oscillation is determined by

A: the amount of the initial displacement.

B: the mass of the thingy and the properties of the spring

C: the local gravitational field, g.

D: all of the above