A smooth ring P of mass m can slide on a fixed horizontal rod. A string tied to the ring passes over a fixed pulley and carries a block Q of mass (mil) as shown in the figure. At an instant, the string between the ring and the pulley makes an angle \[60{}^\circ \]with the rod. The initial acceleration of the ring is

• A. \[\frac{2g}{3}\]  
• B. \[\frac{2g}{6}\]
• C. \[\frac{2g}{9}\]  
• D. \[\frac{g}{3}\]