_Smoker's equation for the calculation of number of equilibrium stages in a continuous binary distillation column is used, when the$?

• A. Relative volatility is close to one (e.g., separation of close boiling isomers)
• B. Feed is not at its bubble point
• C. Number of equilibrium stages in only stripping section is to be calculated
• D. Number of equilibrium stages required is likely to be very small