All pullicys and strings shown in figure are light and there is no friction in any string and pulley.

$($A$)8$ kg

$($B$)9\mathrm{.}6$ kg

$($C$)6\mathrm{.}4$ kg

$($D$)10$ kg

Mass $\text{'}m\text{'}$ to be hanged so that none of the block remains in equilibrium must satisfy $-$

$($A$)m>8kg$

$($B$)m>9\mathrm{.}6kg$

$($C$)m>10kg$

$($D$)m>12kg$

Acceleration of hanging block if mass of hanging block is $9$ kg $-$

$($A$)\frac{9}{31}\frac{m}{s^2}$

$($B$)\frac{10}{31}\frac{m}{s^2}$

$($C$)\frac{10}{41}\frac{m}{s^2}$

$($D$)\frac{11}{32}\frac{m}{s^3}$