The correct answer is: C. Elephant
The flagship species of Choolannur sanctuary is the elephant. The sanctuary is home to a large population of elephants, which are an important part of the ecosystem. Elephants help to disperse seeds and pollinate plants, and they also play a role in controlling the population of other animals.
The other options are incorrect because they are not the flagship species of Choolannur sanctuary. Tiger is the flagship species of Periyar Tiger Reserve, peacock is the national bird of India, and rhino is the flagship species of Kaziranga National Park.
The flagship species of a protected area is an animal or plant that is chosen to represent the area and to raise awareness of its importance. The flagship species should be charismatic and well-known, and it should be an important part of the ecosystem. The choice of flagship species can help to attract visitors to the protected area and to raise funds for its conservation.