Carnot cycle (reversible) of a gas represented by a P-V curve is shown consider the following statements
I. Area ABCD = Work done on the gas
II. Area ABCD = Net heat observed
III. change in the internal energy in cycle = 0
Which of these are correct.
 

• A

  I only

• B

  II only

• C

  II and III

• D

  I, II and III