The set which does not have ambidentate ligand(s) is

$\displaystyle \mathrm{EDTA}^{4-}, \mathrm{NCS}^{-}, \mathrm{C}_2 \mathrm{O}_4{ }^{2-}$

$\displaystyle \mathrm{NO}_2^{-}, \mathrm{C}_2 \mathrm{O}_4{ }^{2-}$, EDTA $\displaystyle { }^{4-}$

$\displaystyle \mathrm{C}_2 \mathrm{O}_4{ }^{2-}$, ethylene diammine, $\displaystyle \mathrm{H}_2 \mathrm{O}$

$\displaystyle \mathrm{C}_2 \mathrm{O}_4{ }^{2-}, \mathrm{NO}_2{ }^{-}, \mathrm{NCS}^{-}$