Which of the following agents is used to remove a molecule of oxygen from a stain?

The correct answer is reducing agents. Reducing agents are substances that can donate electrons to another substance, effectively causing a reduction reaction. In the context of stain removal, reducing agents play a critical role in breaking down certain types of stains by removing oxygen from the molecules involved. This process can lead to the degradation of stain compounds, making them easier to eliminate from the carpet fibers.

Enzymatic agents work differently by using enzymes to break down organic materials in stains rather than focusing on the reduction of oxygen. Oxidizing agents, on the other hand, actually add oxygen to molecules, which can sometimes enhance staining rather than remove it. Surfactants serve to lower the surface tension of water and help in dispersing and removing dirt and grime, but they do not directly remove oxygen from stain molecules. This differentiation highlights the importance of understanding the specific chemical actions that different agents have in the cleaning process.