The acceleration of the blocks (A) and (B) respectively in situation shown in the flgure is: (pulleys and strings are massless)

• A

  $\frac{2\mathrm{g}}{7} \mathrm{downward}, \frac{\mathrm{g}}{7} \mathrm{upward}$

• B

  $\frac{2\mathrm{g}}{3} \mathrm{downward}, \frac{\mathrm{g}}{3}\mathrm{upward}$

• C

  $\frac{10}{13}\mathrm{g} \mathrm{downward}, \frac{5\mathrm{g}}{13}\mathrm{upward}$

• D

  none of these