A substance that is solute in a colloidal stage.AerogelDispersed phaseDispersed mediumBoth B and C

To analyze the nature of a substance that is a solute in a colloidal stage, let's break down the options provided:

1. Aerogel: This is a type of material derived from a gel where the liquid component has been replaced with gas. Aerogels are often used for insulation and other applications, but they are not specifically a solute in a colloidal system.

2. Dispersed phase: In colloid chemistry, this refers to the phase that is dispersed throughout another phase. In a colloidal system, the dispersed phase is typically the solute or particles that are suspended in the medium.

3. Dispersed medium: This is the continuous phase in which the dispersed particles or solute are spread out. It usually refers to the solvent component of the colloid.

4. Both B and C: Since both the dispersed phase and the dispersed medium are relevant to the structure of a colloid, it's essential to understand that both terms are necessary to fully describe the components of a colloidal system.

Based on this breakdown, the best answer is Both B and C, as they both capture aspects of a solute in a colloidal stage. The dispersed phase is the actual solute being dissolved, while the dispersed medium provides the environment in which that solute exists.