$y=ae^{mx}+be^{-mx}$ satisfies which of the following differential equation?

Question

\[(A)\;\frac{dy}{dx}+my=0 \quad (B)\;\frac{dy}{dx}-my=0\quad(C)\;\frac{d^2y}{dx^2}-m^2y=0 \quad (D)\;\frac{d^2y}{dx^2}+m^2y=0\]