Match the solutions to the differential equations. If there is more than one solution to an equation, select the answer that includes all solutions.

 1. $\frac{d^2y}{dx^2}=9 y$
 2. $\frac{d^2y}{dx^2}=-9 y$
 3. $\frac{dy}{dx}=-3 y$
 4. $\frac{dy}{dx}=3 y$

A. $y = \sin(3 x)$
B. $y = e^{3 x}$
C. $y = e^{-3 x}$ or $y = e^{3 x}$
D. $y = \sin(3 x)$ or $y = 3\sin(x)$
E. $y = e^{-3 x}$
F. $y = 3\sin(x)$