The correct option "1 and 3 only" is appropriate because the Blue-finned Mahseer is indeed endemic to the Cauvery River, known for its unique aquatic biodiversity, while the Rusty-spotted Cat is a small felid native to the forests of the Eastern Ghats. However, the Irrawaddy Dolphin, which is typically found in coastal and freshwater environments, is mostly associated with rivers like the Mahakam and certain areas in Myanmar and Southeast Asia, rather than the Chambal River in India. This highlights the importance of habitat specificity for wildlife conservation, a key focus in environmental studies relevant to UPSC Prelims.