Which type of adjuvant functions as a wetting agent and spreader by altering the surface tension of spray droplets?

The correct choice highlights that surfactants serve as effective wetting agents and spreaders by altering the surface tension of spray droplets. This function is crucial in pesticide application, as it enhances the ability of the pesticide to spread evenly over surfaces, such as plant leaves or soil, improving adherence and efficacy.

Surfactants work by reducing the cohesive forces between the molecules in the liquid spray, allowing the droplets to spread out more instead of forming beads. This results in better coverage and penetration of the pesticide into the target area, which is especially important for maximizing contact with pests.

In contrast, other options do not possess the same function. Stickers, for example, are designed primarily to increase the adhesion of the pesticide to the surface rather than altering surface tension directly. Emulsifiers are involved in mixing oil and water but do not specifically function as wetting agents. Buffers regulate the pH of the spray solution but do not play a role in altering surface tension. Thus, surfactants are essential for improving the overall effectiveness of pesticide applications through their wetting and spreading properties.