Which of the following exhibits the greater freezing - point lowering ?

Question

$\begin{array}{1 1} 0.1\;mol\;kg^{-1} \;NaCl \\ 0.1\;mol\;kg^{-1} \;CaCl_2 \\ 0.1\;mol\;kg^{-1} \;HC_2H_3O_2 \\ 0.1\;mol\;kg^{-1} \;NaC_2H_3O_2 \end{array}$