The correct answer is B. Phalgu.
The Phalgu river is a tributary of the Son River in the Indian state of Bihar. It is also known as Nairanjana, which means “the one who gives joy”. The river is sacred to Hindus and is believed to have originated from the hair of Vishnu. It is also said to be the birthplace of the Buddha.
The Phalgu river is a major source of irrigation for the region. It is also used for drinking water and industrial purposes. The river is home to a variety of fish and other aquatic life.
The Phalgu river is a beautiful and important river in India. It is a source of life and livelihood for many people. It is also a place of religious significance.
The other options are incorrect because:
- The Gandak river is a tributary of the Ganges River in the Indian states of Uttar Pradesh and Bihar.
- The Son river is a tributary of the Ganges River in the Indian states of Jharkhand, Bihar, and Uttar Pradesh.
- The Mahananda river is a tributary of the Brahmaputra River in the Indian states of West Bengal and Assam.