During electron transport reactions During electron transport reactions both OH- and H accumulate on the outside of the membrane. OH- accumulates on the outside of the membrane while H accumulates on the inside. OH- accumulates on the inside of the membrane while H accumulates on the outside. both OH- and H accumulate on the inside of the membrane.

OH- accumulates on the inside of the membrane while H accumulates on the outside.

Explanation:

The electron transport chain is the important cycle that helps in the production of ATP molecules by the transfer of electrons to the specific substrate.

The electron transport chain occurs due to the proton motive force. The water molecules are broken down and oxygen acts as the final electron acceptor molecule. The hydroxyl ions that are formed during the direction are accumulated in the inside of mitochondria membrane and hydrogen ions are present on the outside of the membrane.

Thus, the correct answer is option (3).