The reaction representing the Mond process for metal refining is ________.
\( \mathrm{Zr + 2I_2 \xrightarrow{\Delta} ZrI_4} \)
\( \mathrm{Ni + 4CO \xrightarrow{\Delta} Ni(CO)_4} \)
\( \mathrm{2K[Au(CN)_2] + Zn \xrightarrow{\Delta} K_2[Zn(CN)_4] + 2Au} \)
\( \mathrm{ZnO + C \xrightarrow{\Delta} Zn + CO} \)