What atoms (i) in flavoproteins and (ii) in cytochrome C undergo reduction and oxidation in the electron-transport chain?

(i) Flavoproteins: Nitrogen

(ii) Cytochrome C: Iron

(i) Flavoproteins: Iron

(ii) Cytochrome C: Carbon

(i) Flavoproteins: Carbon

(ii) Cytochrome C: Nitrogen

(i) Flavoproteins: Sulfur

(ii) Cytochrome C: Oxygen