Which type of adjuvant is used to modify pH levels in pesticide formulations?

Buffers or pH modifiers are specifically designed to adjust and stabilize the pH levels in pesticide formulations. This modification is crucial because the effectiveness and stability of many pesticides can be significantly influenced by pH. By using buffers, applicators can ensure that the pesticide remains effective throughout the application process and that it interacts appropriately with the target pest or plant.

The other options serve different purposes; drift retardants help reduce the off-target movement of sprays, thickeners increase the viscosity of the solution to improve adhesion and reduce runoff, and extenders prolong the effectiveness of the pesticide but do not specifically focus on pH adjustment.