The correct answer is b) Bharathapuzha Basin.
The Bharathapuzha Basin is the largest river basin in Kerala, covering an area of 21,128 square kilometers. It is the second longest river in Kerala, after the Periyar River. The Bharathapuzha River originates in the Western Ghats and flows through the districts of Palakkad, Thrissur, Malappuram, and Kozhikode. The river is a major source of irrigation and drinking water for the people of Kerala. It is also a popular tourist destination.
The Bharathapuzha Basin has a number of irrigation projects, including the Malampuzha Dam, the Neyyar Dam, and the Idukki Dam. These projects provide irrigation water for over 1 million hectares of land in Kerala. The Bharathapuzha Basin is also home to a number of hydroelectric power plants, including the Pallivasal Hydroelectric Power Plant and the Moolamattom Hydroelectric Power Plant.
The Bharathapuzha Basin is a major source of water for the people of Kerala. It is also a popular tourist destination. The Bharathapuzha River is a beautiful river that flows through the Western Ghats. The river is a popular spot for fishing, swimming, and boating. The Bharathapuzha Basin is a great place to enjoy the natural beauty of Kerala.
The other options are incorrect because they are not the largest river basins in Kerala. The Periyar Basin is the second largest river basin in Kerala, covering an area of 16,000 square kilometers. The Chalakudy Basin is the third largest river basin in Kerala, covering an area of 12,000 square kilometers. The Pamba Basin is the fourth largest river basin in Kerala, covering an area of 10,000 square kilometers.