The correct option is A Wholesale Price Index
1:In India, Consumer Price Index (CPI) and Wholesale Price Index (WPI) are two major indices for measuring inflation. In United States, CPI and PPI (Producer Price Index) are two major indices.
2:The Wholesale Price Index (WPI) was main index for measurement of inflation in India till April 2014 when RBI adopted new Consumer Price Index (CPI) (combined) as the key measure of inflation.