Explanation

In pesticide and agricultural formulations, an adjuvant is specifically used to enhance the performance of the active ingredient, often by diluting or carrying it. A carrier is a bulk inert material that holds the active ingredient but is not primarily defined as the substance used to 'dilute' in the functional sense implied here, though carriers do provide volume. However, standard agricultural chemistry definitions state that adjuvants are added to improve efficacy, while carriers are inert substances used to dilute or carry the active ingredient. Wait, let's re-evaluate. In many contexts, especially pesticides, the 'carrier' is the inert material that dilutes the active ingredient. An 'adjuvant' is an additive that improves performance but is not necessarily a diluent. Let's check standard definitions. Carrier: A substance used to dilute or carry the active ingredient. Adjuvant: A substance added to a pesticide formulation to improve its physical properties or efficacy. The question asks for a material used to 'dilute' active material. This points strongly to Carrier. However, some sources might use Adjuvant loosely. Let's look at common MCQs for this topic. Many agricultural extension MCQs define 'Carrier' as the inert material that dilutes the active ingredient. Therefore, C is likely correct. I will stick with C.