Cytochrome oxidase has which of the following metal as prosthetic group?

Cytochrome oxidase is a hemoprotein widely distributed in many tissues. It is the terminal component of the chain of respiratory carriers found in mitochondria (and transfers electrons resulting from the oxidation of substrate molecules by dehydrogenases to their final acceptor, oxygen. It contains two molecules of heme, each having one Fe atom that oscillates between Fe3+ and Fe2+ during oxidation and reduction. Fuhermore, two atoms of Cu are present, each associated with a heme unit. Ref: Harper 28th edition, chapter 12.