During a thunderstorm, a plasma channel forms between the negatively charged clouds and the positively charged Earth, which creates lightning. When lightning is observed, what has passed through the plasma channel?

Lightning is an electrical discharge: electrons move through the ionized plasma channel between the negatively charged cloud and the positively charged Earth. Atoms, nitrogen, and water may be present in the air, but the moving electric charges are electrons. Therefore, the correct choice is electrons.

AI-written and checked against the verified answer.