Verify That $y=-2 \cos (5 t)$ Is a Solution Of $y^{\prime \prime}=-25 y$

Multiple Choice

Verify that $y=-2 \cos (5 t)$ is a solution of $y^{\prime \prime}=-25 y$ .Suppose that y describes the motion of a mass on a spring. How does the motion start when t = 0?

A) lowest point
B) in the middle
C) highest point