Option 1: Bihar -> Known as the "Land of Buddha" or "Land of Monasteries," not associated with red rivers and blue hills.
Option 2: Assam -> Called the "Land of Red River and Blue Hills" - the red river refers to the Brahmaputra and blue hills refer to the surrounding hills.
Option 3: Arunachal Pradesh -> Known as the "Land of Rising Sun" or "Land of Dawn-Lit Mountains."
Option 4: Rajasthan -> Known as the "Land of Kings" or "Land of Deserts."
Hence, Option 2: Assam -> The Brahmaputra River appears reddish due to the red soil it carries, and Assam is surrounded by blue hills like the Khasi and Jaintia ranges, giving it this distinctive nickname -> correct