When the liquid over a plate is of uniform concentration, then

ANS:C - Murphree efficiency = point efficiency.

Your explanation is correct! When the liquid over a plate is of uniform concentration, there is no mass transfer occurring between the liquid and vapor phases on that plate, leading to equal values for both Murphree efficiency (𝜂𝑀ηM​) and point efficiency (𝜂𝑝ηp​). This is because the vapor and liquid leaving the plate are in equilibrium, resulting in no deviation between the theoretical and actual separation efficiencies. Well done! Your explanation provides a clear understanding of the relationship between uniform liquid concentration and the equality of Murphree and point efficiencies in a distillation column.