What characterizes water-soluble powders?

Water-soluble powders are specifically characterized by their ability to completely dissolve in water to form a homogeneous solution. This means that when the powder is added to water, it fully incorporates into the liquid, resulting in a clear solution without any undissolved particles. This property is essential in many agricultural and aquatic applications, as it allows for consistent distribution of the active ingredients throughout the water, ensuring effective treatment and coverage.

In contrast, the other choices describe different characteristics of other types of formulations. Some formulations may only partially dissolve, which would not meet the criteria for being considered water-soluble powders. Granular pesticides that cannot mix with water indicate a different formulation type, typically with a solid base that lacks solubility in an aqueous environment. Dust formulations, while they may mix with water, require agitation for dispersion, which is not a defining trait of water-soluble powders. Thus, the ability of water-soluble powders to fully dissolve is what distinguishes them and makes Option B the correct answer.