The phase diagrams for the pure solvent (solid lines) and the solution (non-volatile solute, dashed line) are recorded below. The quantity indicated by ‘L’ in the figure is

In the given diagram depicting the phases of pure solvent (solid lines) and the solution (non-volatile solute, dashed line), L indicates the elevation in boiling point. The elevation in boiling point is represented using notation ${\mathrm{K}}_{\mathrm{b}}.\mathrm{m}$, making option C the required answer.