PLEASE HURRY!!!Which common characteristic makes both batteries and fuel cells practical to use?
They are portable resources that convert chemical energy to electrical energy.
They use a continual source of outside reactants to change chemical energy to electrical energy.
They are self-contained producers of chemical energy.
They are sources of energy that do not need to be recharged.

Batteries are sets of batteries connected in series, that is, they are electrochemical devices in which oxidation reduction reactions (chemical energy) occur, producing an electric current (electrical energy). They can also be called secondary batteries, secondary batteries or accumulators.

Fuel cells, in turn, also transform chemical energy into electrical energy, and their operation produces low environmental impact: no vibrations, no noise, no combustion, no emission of particulates and, depending on the technology, no emission of greenhouse gases. In addition, in the current stage of development, without emission of acid gases and with low pollution.

With that, we can say that batteries and fuel cells are practical because they are portable resources that convert chemical energy into electrical energy.