A thermally insulated vessel is partitioned into two compartments by a rigid, movable, and frictionless diathermal (heat conducting) piston. Each compartment contains one mole of an ideal gas. The piston is initially clamped and the temperature, pressure, and volume of the gases in the first and second compartments are: $T_1=400 \mathrm{~K}, V_1=2$ L ; and $T_2=200 \mathrm{~K}, V_2=4 \mathrm{~L}$. The piston is then released and the system is allowed to attain thermodynamic equilibrium in both the compartments. The correct figure(s) depicting this spontaneous process, is/are: (work associated with the movement of the piston may be neglected)

• A

  
  
• B

  
  
• Correct answer
  C

  
  
• Correct answer
  D

  
  

Hence, the correct answer is options: 'C', 'D'.