Giải phương trình \(\left( {2\cos \frac{x}{2} - 1} \right)\left( {\sin \frac{x}{2} + 2} \right) = 0\) ?

A. \(x =  \pm \frac{{2\pi }}{3} + k2\pi ,\,\left( {k \in Z} \right)\)

B. \(x =  \pm \frac{\pi }{3} + k2\pi ,\,\left( {k \in Z} \right)\)

C. \(x =  \pm \frac{\pi }{3} + k4\pi ,\,\left( {k \in Z} \right)\)

D. \(x =  \pm \frac{{2\pi }}{3} + k4\pi ,\,\left( {k \in Z} \right)\)