The block $A$ has mass $m_{1}$ and is attached to a spring having a stiflness $k .$ The natural length of the spring is $I_{0}$. Another block $B$ of mass $m_{2}$ is pressed against block $A$ so the compression in the spring is $d$. The arrangement is released from rest from this position. The coeflicient of friction between the blocks and the ground beneath is $\mu$. The block $B$ will gel separated from $A$ il
(a) $d \leq \frac{2\left(m_{1}+m_{2}\right) \mu g}{k}$
(b) $d \leq \frac{\left(m_{1}+m_{2}\right) \mu g}{k}$
(c) $d>\frac{2\left(m_{1}+m_{2}\right) \mu g^{1 / 2}}{k}$
(d) $d>\frac{\left(m_{1}+m_{2}\right) \mu g}{k}$