In comparing the flow rate of liquids with differing viscosities, which liquid has the lowest flow rate?

The correct choice highlights that the liquid with the highest viscosity will have the lowest flow rate. Viscosity is a measure of a fluid's resistance to flow: the higher the viscosity, the thicker the liquid, and the more it resists motion. This resistance means that a highly viscous liquid will flow more slowly compared to liquids with lower viscosities, which flow more freely and quickly.

In many practical applications, such as in aerial application of pesticides, recognizing the impact of viscosity on flow rates is crucial for ensuring proper application rates and achieving effective pest control while minimizing environmental impact. Thus, when considering which liquid has the slowest flow due to its physical properties, the one with the highest viscosity clearly stands out as the correct answer.