What does a reducing agent do?

A reducing agent is a substance that donates electrons to another substance in a chemical reaction, facilitating the reduction process. When a reducing agent donates electrons, it causes the oxidation state of another substance to decrease, meaning that this substance is being reduced. Simultaneously, the reducing agent itself is undergoing oxidation, which is the process of losing electrons and increasing its oxidation state.

In this context, the correct choice emphasizes the dual role of the reducing agent in the reaction—it both reduces another substance and is oxidized in the process. The characteristics of reducing agents are crucial in redox (reduction-oxidation) reactions, where the flow of electrons between substances determines the outcome of the reaction.

Other options do not accurately describe the role of a reducing agent. For instance, increasing the oxidation state of another substance would describe an oxidizing agent, while the statement about not participating in reactions is fundamentally incorrect, as reducing agents are integral to the redox process. Lastly, providing oxygen to reactions pertains more to combustion or oxidation processes rather than the function of a reducing agent.