Correct Answer: (a) Both the base year and calculation method have changed.
Solution:The CSO, in 2015, replaced the GDP series with the base year 2004-05 with a new series that used 2011-12 as a baseline for national accounts. In the new series, the CSO did away with Gross Domestic Product (GDP) at factor cost and adopted the international practice of valuing industry-wise estimates as Gross Value Added (GVA) at basic prices. The new series has followed the guidelines of the United Nations' System of National Accounts (UNSNA) 2008, replacing the earlier template of UNSNA 1994. Thus, option (a) is the right answer.