Solution:A tax-to-GDP ratio is a gauge of a nation's tax revenue relative to the size of its economy as measured by gross domes- tic product (GDP). Slowing economic growth rate may result in lower tax collection but it does not necessarily mean decrease in tax-GDP ratio. Whether the fall in tax collection is proportionate to the fall in GDP cannot be known without knowing the all indices.Hence, statement 1 is incorrect. If the distribution of national income is not equitable, it may mean a perennial low tax-GDP ratio, but it could not mean a decrease in tax-GDP ratio over the years.
A decrease in tax-GDP ratio is a short-term phenomenon and it can be affected by a number of reasons including tax avoidance,tax evasion, less efficient methods of tax collection etc. as well as by structural reasons. Hence, statement 2 is also incorrect.
Note: UPSC had given option (a) as the correct answer of this question in its official answer key.