Which half reaction shows both the conservation of mass and the conservation of charge?

I will explain it with two figures. So, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as system's mass cannot change, so quantity cannot be added nor removed. As shown in Figure 1, the system S1 is closed. Both a) and b) have the same quantity of mass. The only thing is happening here is a mass and energy transfer.
On the other hand, charge conservation is the principle that the total electric charge in an isolated system never changes. The net quantity of electric charge, the amount of positive charge minus the amount of negative charge in the universe, is always conserved. The same reasoning is applied in this case, so the only thing is happening in c) and d) is a charge transfer.
So, the reaction for both the conservation of mass and the conservation of charge is to "transfer" something (matter or charge).

Answerinternal combustion engine fuel;