In an ionic solution such as salt water, which charges carry the current?

1. Charge carriers differ from one conducting medium to another. 2. In metal wires the mobile carriers are free electrons, so only negative charge moves there. 3. In an ionic solution both positive and negative ions are free to move, and both contribute to the current. 4. The same two way motion happens in nerve cells, so the solution case is not a special exception. 5. Options one and two each describe only half of what happens in salt water. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.1 Current_