The statement regarding Purchasing Power Parity (PPP) exchange rates is correct because PPP is based on the idea that identical goods should have the same price when expressed in a common currency. This allows for better comparisons of economic productivity and standards of living between countries. The assertion that India is the sixth largest economy in terms of PPP dollars might not be up to date or universally accepted, as rankings fluctuate with economic changes; hence the correct option focuses solely on the accurate explanation of the PPP concept, reflecting a deeper understanding essential for UPSC examination preparation.