What is meant by the term 'active ingredient' in a pesticide?

The term 'active ingredient' refers specifically to the component of a pesticide formulation that is responsible for controlling pests and possesses toxicity. This is the chemical that interacts with the pest to cause the desired effect, such as killing, repelling, or disrupting its growth.

Active ingredients are the primary substances intended to impact the target organisms, whereas other components in the formulation, such as inert ingredients and additional components, play supporting roles. Inert ingredients can enhance the effectiveness or stability of the pesticide but do not contribute to its pest-control function. Thus, option B accurately captures the essential role of the active ingredient in pest control products.