Correct Answer: Periyar

Solution : The correct answer is Periyar .

The Periyar River is the longest in the state of Kerala. It is also known as the lifeline of Kerala. The major tributaries of the Periyar are Muthirapuzha River, Mullayar River and Cheruthoni River. It originates in the Western Ghats. It is one of the few perennial rivers in the region and provides drinking water for several major towns.