Relative lowering of vapor pressure is a colligative property, which means it depends on the number of particles in a solution rather than their nature. It is defined as the ratio of the decrease in vapor pressure of a solvent to the vapor pressure of the pure solvent. This property is directly related to the concentration of solute particles in a solution.

Explanation:

Colligative Properties:
- Colligative properties are properties of a solution that depend on the number of solute particles present, rather than the specific type of solute.
- These properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.

Vapor Pressure:
- Vapor pressure is the pressure exerted by the vapor molecules above the surface of a liquid in a closed container at equilibrium.
- It is a measure of the tendency of molecules to escape from the liquid phase and enter the vapor phase.

Relative Lowering of Vapor Pressure:
- The relative lowering of vapor pressure is defined as the ratio of the decrease in vapor pressure of the solvent in the presence of a non-volatile solute to the vapor pressure of the pure solvent.
- It can be calculated using the formula: Relative Lowering of Vapor Pressure = (P° - P) / P°, where P° is the vapor pressure of the pure solvent and P is the vapor pressure of the solvent in the presence of the solute.

Number of Particles:
- According to Raoult's Law, the vapor pressure of a solvent is directly proportional to the mole fraction of the solvent in the solution.
- When a non-volatile solute is added to the solvent, it lowers the vapor pressure of the solvent.
- The extent of vapor pressure lowering depends on the number of solute particles present in the solution.

Explanation of the Correct Answer:
- The relative lowering of vapor pressure is equal to the ratio between the number of solute molecules to the total molecules in the solution.
- This is because the vapor pressure of the solvent is affected by the presence of solute particles, and the relative lowering of vapor pressure is a measure of this effect.
- The more solute particles there are in the solution, the greater the decrease in vapor pressure of the solvent.
- Therefore, option B is the correct answer as it correctly represents the relationship between the number of solute molecules and the relative lowering of vapor pressure.

In conclusion, the relative lowering of vapor pressure is directly related to the ratio between the number of solute molecules to the total molecules in the solution. This colligative property depends on the concentration of solute particles and is independent of the nature of the solute.