\(y = x.\sin x + \sqrt {1 + {{\cos }^2}2x} \)
A.\(y' = \sin x + x\cos x + \dfrac{{ - \sin 4x}}{{\sqrt {1 + {{\cos }^2}2x} }}\)
B.\(y' = \sin x + x\cos x - \dfrac{{ - \sin 4x}}{{\sqrt {1 + {{\cos }^2}2x} }}\)
C.\(y' = \sin x - x\cos x + \dfrac{{ - \sin 4x}}{{\sqrt {1 + {{\cos }^2}2x} }}\)
D.\(y' = \sin x - x\cos x - \dfrac{{ - \sin 4x}}{{\sqrt {1 + {{\cos }^2}2x} }}\)