In a chemical reaction where substance A transfers electrons to substance B, the following statements are true:
- Substance A loses electrons and is oxidized.
- Substance B gains electrons and is reduced.
In this context, substance A acts as the reducing agent (since it donates electrons) and substance B acts as the oxidizing agent (since it accepts electrons).
Therefore, the correct statement is:
Substance A is oxidized and acts as the reducing agent. Substance B is reduced and acts as the oxidizing agent.