What balances charges that may build up as reduction and oxidation occur in a voltaic cell?
a.
the salt bridge
c.
the electrolyte solutions
b.
one of the half-cells
d.
the moving electrons

I think the correct answer from the choices listed above is option A. It is the salt bridge that balances charges that may build up as reduction and oxidation occur in a voltaic cell. The salt bridge is to maintain charge balance because the electrons are moving from one half cell to the other.

Idkat all because idhducheh