If \(x\sin \theta = y\sin \left( {\theta + \frac{{2\pi }}{3}} \right) = z\sin \left( {\theta + \frac{{4\pi }}{3}} \right)\), Then xy + yz + zx is equal to

• A. 1
• B. \(\frac{1}{2}\)
• C. 0
• D. None of these