Directions: Question numbers 28, 29 and 30 are based on the following paragraph. Two moles of helium gas are taken over the cycle ABCDA, as shown in the P – T diagram.

Two moles of helium gas are taken over the cycle $ABCDA$, as shown in the $P–T$ diagram. Assuming the gas to be ideal, the work done on the gas in taking it from $A$ to $B$ is:

1. A
   $200R$
2. B
   $300R$
3. C
   $400R$
4. D
   $500R$