Which two factors are essential in determining how an active ingredient is formulated?

The correct answer highlights the importance of solubility and intended use in the formulation of an active ingredient. Solubility is crucial because it affects how well the active ingredient can be mixed with water or other solvents, which is essential for effective application. If an active ingredient is not soluble, it may not disperse properly, leading to uneven application or reduced efficacy against target weeds or pests.

Intended use plays a significant role as well since it determines the method of application, the environment where the herbicide will be used, and the target species. For example, herbicides used for agricultural purposes may need to be formulated differently compared to those intended for residential lawn care due to variations in the types of plants, application techniques, and environmental conditions.

While other factors, such as stability, availability, concentration, toxicity, cost, and shelf-life, may influence formulation decisions, solubility and intended use are directly tied to the core functionality and effectiveness of the herbicide in practice.