Ghaghara is a tributary of which river system?

Correct answer: Ganga system

The direct answer is D, the Ganga system. Ghaghara is a major tributary of the Ganga, joining the Ganga in the northern plains. A tributary is a smaller river that flows into a larger river. To solve this, identify the river system to which Ghaghara belongs: Ghaghara flows through the Himalayan and northern plain region, receives water from its own smaller streams, and finally joins the Ganga. Therefore it is part of the Ganga drainage system. Option A, the Krishna system, is incorrect because Krishna is a peninsular river of southern India and Ghaghara is not its tributary. Option B, the Narmada system, is incorrect because Narmada flows westward through central India, whereas Ghaghara belongs to the northern Himalayan drainage network. Option C, the Godavari system, is incorrect because Godavari is a separate peninsular river system. Option D is correct because Ghaghara is a left-bank tributary of the Ganga. A useful exam cue is to remember Ghaghara, Gandak and Kosi together as important northern tributaries of the Ganga. Do not confuse a tributary with a river system: the tributary is the smaller river, while the Ganga system includes the main river and its tributaries.