General solution of differential equation $$\frac{dy}{dx} = \cos(x + y)$$ is

A

$$\tan\left(\frac{x + y}{2}\right) = y + c$$

B

$$\sin\left(\frac{x + y}{2}\right) = y + c$$

C

$$\cos\left(\frac{x + y}{2}\right) = x + c$$

D

$$\tan\left(\frac{x + y}{2}\right) = x + c$$