Two blocks A and B of masses $3\;m$ and $m$ respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively :

Question

$\begin{array}{1 1} (1) g, \frac{g}{3} \\ (2) \frac{g}{3},g \\ (3) g,g \\ (4) \frac{g}{3},\frac{g}{3} \end{array}$