A businessman wants to make some profit by selling a certain item. He thinks about several methods to make profit. Which of the following would maximize his profit?

1. ISell that item at 10% profit.
2. IIUse an incorrect weight which is 100 grams less than 1 kg, but is marked as 1 kg.
3. IIIMix 10% impurities in that item and sell that item at cost price.
4. IVIncrease the price by 5%, and use an incorrect weight whose real value is 5% less than what is marked on it.