What type of adjuvant acts as a wetting agent and spreader?

The correct answer is surficant because its primary functions include acting as a wetting agent and spreader. Surfactants, which stands for "surface-active agents," reduce the surface tension of water, allowing the spray solution to spread more evenly over surfaces, such as plant leaves. This improves the efficacy of pesticide applications by ensuring better contact and coverage.

In contrast, emulsifiers are responsible for stabilizing mixtures of oil and water, which is essential in forming emulsions, but they do not specifically serve as wetting agents or spreaders. Sticking agents are designed to help herbicides or pesticides adhere to their target surfaces, reducing the likelihood of runoff, but they do not necessarily improve wetting or spreading capabilities. Penetrants aid in facilitating the absorption of pesticides through plant tissues, enhancing the movement of the chemical into the plant, but they do not perform the spreading and wetting roles that surfactants do.