Final answer:
The oxidizing agent in a chemical reaction is the substance that gets reduced by gaining electrons, causing another substance to be oxidized. The oxidizing agent in a chemical reaction is best described by option D) the substance that is reduced because it gains electrons.
Step-by-step explanation:
The oxidizing agent in a chemical reaction is best described by option D) the substance that is reduced because it gains electrons. In a chemical reaction involving oxidation-reduction (redox) processes, two key players are the oxidizing agent and the reducing agent. The oxidizing agent is the substance that causes oxidation by accepting electrons and, as a result, is itself reduced. Conversely, the reducing agent causes reduction by losing electrons and is thus oxidized. For example, in a reaction where zinc is oxidized by losing electrons, if sulfur is the substance that gains those electrons, then sulfur is the oxidizing agent. This is because sulphur's oxidation state decreases as it accepts electrons and causes zinc to be oxidized.
An oxidizing agent is a substance that causes oxidation by accepting electrons; therefore, it gets reduced. A reducing agent is a substance that causes reduction by losing electrons; therefore it gets oxidized. Examples of how to identify oxidizing and reducing agents are shown.