Left pan of a faculty balance weighs 100 gms more than its right pan. A shopkeeper keeps the weight measure in the left pan while buying goods but keeps it in the right pan while selling his goods. He uses only 1 kg weight measure. If he sells his goods at the listed cost price, what is his gain ?

• A. 100/11%
• B. 200/11%
• C. 100/9%
• D. 200/9%