The equilibrium constants K_P and K_c for a gaseous reaction are related to each other through the expression

The equilibrium constants for a gaseous reaction are related to each other through the expression  is ${\mathrm{K}}_{\mathrm{p}}={\mathrm{K}}_{\mathrm{c}}(\mathrm{RT}{)}^{{\mathrm{\Delta n}}_{\mathrm{g}}}$

A number that represents the proportionality of the reactant and product concentrations at equilibrium in a reversible chemical reaction at a specific temperature.

Hence option B is correct.