Which of the following is correct order of ligand field strength?
\( \mathrm{S^{2-}} < \mathrm{NH_3} < \mathrm{en} < \mathrm{CO} < \mathrm{C_2O_4^{2-}} \)
\( \mathrm{NH_3} < \mathrm{en} < \mathrm{CO} < \mathrm{S^{2-}} < \mathrm{C_2O_4^{2-}} \)
\( \mathrm{CO} < \mathrm{en} < \mathrm{NH_3} < \mathrm{C_2O_4^{2-}} < \mathrm{S^{2-}} \)
\( \mathrm{S^{2-}} < \mathrm{C_2O_4^{2-}} < \mathrm{NH_3} < \mathrm{en} < \mathrm{CO} \)