Answer
The answer is below.
Work Step by Step
We know that $F=-kx$. This means that the force, and subsequently the acceleration, will be 0 when the compression of the spring is 0. Thus, when the spring is in its natural uncompressed position, the force will be 0. The velocity will be 0 when the system changes direction. This occurs when the spring is completely stretched and when it is completely compressed.
