The general solution of the differential equation \(\frac{{dy}}{{dx}} = \cos \left( {x + y} \right)\), with c as a constant, 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. \(\tan \left( {\frac{{x + y}}{2}} \right) = x + c\)