Answer:
By checking all commodities.
Explanation:
I have to conduct an investigation by comparing prices of all commodities with the standard market price. I have to check the presence of double prices on the single commodities. Those commodities which have more than one price and that were over priced will be send to the factory for correction in order to remove inconvenience occur to the customer. I have to check all the commodities to remove the error in them.
The Answer is, Underground
