The 2.56gm of sulphur in 100gm of $CS_2$ has depression in freezing point of $0.010^{\large\circ}$C. $K_f=0.1^{\large\circ}C$/molal. Hence atomicity of sulphur in $CS_2$

Question

$\begin{array}{1 1}(a)\;6\\(b)\;4\\(c)\;8\\(d)\;2\end{array}$