If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the

Answer: Option B

The Clausius-Clapeyron equation for the equilibrium between liquid and vapor is then
$$\frac{dp}{dT}=\frac{L}{\left(T\left(V_v-V_l\right)\right)}$$
Where $$L$$ is the latent heat of evaporation, and $$V_v$$ and $$V_l$$ are the specific volumes at temperature $$T$$ of the vapor and liquid phases, respectively.
More generally the Clausius-Clapeyron equation pertains to the relationship between the pressure and temperature for conditions of equilibrium between two phases. The two phases could be vapor and solid for sublimation or solid and liquid for melting.