Which statements about complex IV are true?

This complex catalyzes the reduction of oxygen to water.

Despite consuming protons, this complex pumps H$+$ across the membrane at a rate of $4$ per molecule of O$2$ reduced.

Protons flow down the gradient to the inner membrane space.

Conformational changes as electrons flow through the complex heme centers alter the ability of some residues to bind protons.

View Available Hint$($s$)$for Part A

Statements $1$ and $4$ are correct.Statements $2,3,$ and $4$ are correct.Statements $1,2,$ and $3$ are correct.Statements $1,2,$ and $4$ are correct.