Which river originates from Yamunotri and meets the Ganga at Prayagraj?

e Yamuna is the longest tributary of the Ganga. Option A (“Chambal”) is incorrect because it does not match the river basin, lake type, location, tributary relationship, project or hydrological feature specified in the question. Option B (“Betwa”) is incorrect because it does not match the river basin, lake type, location, tributary relationship, project or hydrological feature specified in the question. Option D (“Tons”) is incorrect because it does not match the river basin, lake type, location, tributary relationship, project or hydrological feature specified in the question. The key concept is to match the water body with its basin, type, location and defining feature. Therefore the correct option, index and explanation consistently identify Yamuna. The Yamuna River originates from the Yamunotri Glacier in Uttarakhand and flows through Uttarakhand, Himachal Pradesh, Delhi, Haryana, and Uttar Pradesh before meeting the Ganga at Triveni Sangam in Prayagraj. The Yamuna is the longest tributary of the Ganga.