Which of the following substances is an example of an herbicide?

Glyphosate is a well-known herbicide used to control weeds and grasses that compete with crops. It works by inhibiting a specific enzyme pathway that is necessary for plant growth but is not found in humans or animals, making it effective for agricultural use while minimizing harm to non-target organisms. Glyphosate has gained significant attention for its wide application and controversies surrounding its safety and environmental impact.

Dieldrin, while a pesticide, is primarily an insecticide and does not specifically target weeds. Potassium pentothal, often used as an anesthetic, is not related to herbicide functions. Narcotics refer to a class of drugs that primarily affect the central nervous system and are unrelated to herbicides.