When $20\;g$ of naphthoic acid $(C_{11}H_gO_2)$ is dissolved in $50 \;g$ of benzene $(K_t =1.72\;K\;kg\;mol^{-1}).$, a freezing point depression of $2 K$ is observe. The van't Hoff factor (i) is

Question

$\begin{array}{1 1} 0.5 \\ 1 \\ 2 \\ 3 \end{array} $