Which of the following is not a valid assumption in continuous binary distillation for calculating the number of equilibrium stages by Mc-Cabe-Thiele's method?

• A. Sensible heat changes for vapour & liquid are negligibly small
• B. Reflux is not a saturated liquid
• C. Molar latent heat of the two components are equal
• D. Heat of mixing of normal liquid is assumed to be zero