The complete solution of the linear differential equation $$\frac{d^{2} y}{dx^{2}}+(a+b)\frac{dy}{dx}+aby=0$$

A

$$C_{1}e^{-ax}+c_{2}e^{-bx}$$

B

$$C_{1}e^{ax}+c_{2}e^{bx}$$

C

$$C_{1}e^{-ax}-c_{2}e^{-bx}$$

D

$$C_{1}e^{ax}-c_{2}e^{bx}$$