Option a is the correct answer. The Niranjana River flows through Bodhgaya. It is believed that the Buddha bathed in the river before he began his meditation under the Bodhi tree. Bodhgaya is a town in the Indian state of Bihar. It is considered to be the holiest site in Buddhism because it is the place where the Buddha attained enlightenment. The Bodhi tree, under which the Buddha attained enlightenment, is located in Bodhgaya. The town is also home to many other Buddhist temples and monasteries.