The correct answer is: C. Gandak
The Triveni Canal is a canal in India that receives water from the Gandak River. It is a major irrigation canal in the state of Bihar. The canal was built in the early 1900s to provide irrigation to the Gangetic Plain. It is one of the largest canals in India, with a length of over 200 kilometers. The canal starts at the Gandak Barrage on the Gandak River in the state of Bihar. It then flows through the states of Uttar Pradesh and Madhya Pradesh before terminating in the state of Rajasthan. The canal irrigates over 1 million hectares of land. It also provides drinking water to over 10 million people.
The other options are incorrect because they are not rivers that the Triveni Canal receives water from. The Sone River is a river in India that flows through the states of Madhya Pradesh, Chhattisgarh, Jharkhand, and Bihar. The Kosi River is a river in India that flows through the states of Nepal and India. The Mayurakshi River is a river in India that flows through the states of West Bengal and Jharkhand.