The correct answer is: C. Gandak
The Triveni canal is a canal in India that was constructed on the Gandak River. It is a major irrigation canal in the state of Bihar. The canal was constructed in the early 1900s to provide irrigation to the Gangetic Plain. It is one of the largest canals in India, and it is a major source of irrigation for the state of Bihar.
The Triveni canal is a gravity canal, which means that it is fed by the Gandak River through a series of locks. The canal is about 200 kilometers long, and it has a capacity of about 10,000 cubic meters per second. The canal is used to irrigate about 1 million hectares of land in the state of Bihar.
The Triveni canal is a major source of water for the state of Bihar. It is used to irrigate crops, and it is also used for drinking water and industrial purposes. The canal is a vital part of the economy of the state of Bihar.
The other options are incorrect because they are not rivers on which the Triveni canal has been constructed. The Kosi River is a river in India that flows through the states of Bihar and Uttar Pradesh. The Son River is a river in India that flows through the states of Madhya Pradesh, Chhattisgarh, Jharkhand, and Bihar. The Kamla River is a river in India that flows through the states of Madhya Pradesh and Chhattisgarh.