一谐振子作振幅为A的谐振动，它的动能与势能相等时，它的相位和坐标分别为:A. pm (pi)/(3); pm (2pi)/(3); pm (A)/(2)B. pm (pi)/(4); pm (3pi)/(4); pm (sqrt(2)A)/(2)C. pm (pi)/(3); pm (2pi)/(3); pm (sqrt(3)A)/(2)D. pm (pi)/(6); pm (5pi)/(6); pm (sqrt(3)A)/(2)

A. $\pm \frac{\pi}{3}; \pm \frac{2\pi}{3}; \pm \frac{A}{2}$

B. $\pm \frac{\pi}{4}; \pm \frac{3\pi}{4}; \pm \frac{\sqrt{2}A}{2}$

C. $\pm \frac{\pi}{3}; \pm \frac{2\pi}{3}; \pm \frac{\sqrt{3}A}{2}$

D. $\pm \frac{\pi}{6}; \pm \frac{5\pi}{6}; \pm \frac{\sqrt{3}A}{2}$