The number of H+ ions moving down the channel.
So id say the answer is C.
Lysosomes break down food and worn out cell parts
While active transportrequires energy and work, passive transportdoes not. There are several different types of this easy movement of molecules. It could be as simple as molecules moving freely such as osmosis or diffusion. You may also see proteins in the cell membrane that act as channels to help the movement along. And of course there is an in-between transport process where very small molecules are able to cross asemi-permeable membrane.
