What is one factor that must be determined before applying herbicides to ensure proper delivery?

The correct choice emphasizes the importance of the type of carrier used in the application of herbicides. The carrier, such as water or oil, serves as the medium through which the herbicide is delivered to the target area or plant. Different carriers can affect the effectiveness, absorption, and mobility of the herbicide. For instance, some herbicides require specific carriers to enhance their efficacy or to ensure that they remain stable and do not degrade before reaching the target. The choice of carrier will also influence factors like the dilution rate, the overall efficacy, and how well the herbicide binds to the target area.

In contrast, considerations such as delivery rate of the equipment, weather conditions, and area size also play important roles in the application process, but they don't specifically pertain to the direct characteristics and behavior of the herbicide itself. The delivery rate is influenced by the type of equipment used, while weather conditions can dictate optimal application times and affect drift or evaporation. Area size is pertinent for planning the application but does not inherently relate to the choice of carrier. Thus, identifying the correct type of carrier is crucial for ensuring that herbicides are applied effectively and safely.