Q. A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state,

• (A) Composition of vapors and that of liquid do not vary throughout the column
• (B) Reboiler load and condenser load are minimum
• (C) The top and bottom compositions are unchanged with and without total reflux
• (D) The top and bottom compositions correspond to the maximum enrichment available