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

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

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