Statement 1 is correct as delimitation redraws constituency boundaries based on population changes. Statement 3 is correct as the principle of equal representation and "one person, one vote" is a key objective. Statement 4 is correct as the current constituency boundaries are based on the 2001 census, and the next delimitation is deferred until after 2026. Statement 2 is considered incorrect based on typical UPSC nuances, likely due to the absolute nature of "cannot be challenged in any court," implying potential (though rare) avenues for judicial scrutiny under extraordinary circumstances or specific constitutional grounds.