Which of the following rivers originates in Nepal and then flows southwards into India to join the Ganges river system?

Introduction / Context:
This question checks your understanding of the major rivers of the Indian subcontinent, particularly those that originate outside India and then join the Ganges system. Knowing the source region and course of such rivers is important for understanding floods, sediment transport, and interstate water issues. The river Kosi is especially famous in Indian geography due to its frequent flooding in Bihar.

Given Data / Assumptions:

• We are asked about a river that originates in Nepal.
• The same river later enters India and joins the Ganges.
• Options include Kosi, Jhelum, Chenab and Ravi.
• We assume standard river system facts used in school geography.

Concept / Approach:
Among the Himalayan rivers listed, Kosi is well known as a tributary of the Ganga that rises in the Himalayas of Nepal, flows through that country and then enters India, mainly affecting Bihar. Jhelum, Chenab and Ravi are part of the Indus river system and have their sources in regions like Kashmir and Himachal Pradesh, not primarily in Nepal. Therefore, identifying the correct river requires linking “Nepal origin” and “tributary of Ganga” together, which points directly to Kosi.

Step-by-Step Solution:
Step 1: Recall that the Ganges river system has several major Himalayan tributaries like Yamuna, Ghaghara, Gandak and Kosi. Step 2: Among these, the Kosi river is famous as a river that originates in the high Himalayas of Nepal. Step 3: The Kosi flows from Nepal into India and ultimately joins the Ganga in Bihar. Step 4: Check the other options: Jhelum, Chenab and Ravi belong to the Indus river system, not the Ganga system. Step 5: Conclude that Kosi is the only option satisfying both conditions of origin in Nepal and confluence with the Ganges.

Verification / Alternative Check:
A quick cross-check is to recall the nickname “Sorrow of Bihar,” which is often used for the Kosi river due to its devastating floods and shifting course on the plains of Bihar. This nickname is frequently mentioned in textbooks and news reports, reinforcing that Kosi is a major Nepal-India transboundary river feeding into the Ganga system. No similar association exists for Jhelum, Chenab or Ravi with Nepal or the Ganges, which confirms the correctness of Kosi as the answer.

Why Other Options Are Wrong:
Option b (Jhelum) is part of the Indus system and mainly flows through Kashmir and Pakistan. Option c (Chenab) also belongs to the Indus system and flows through Himachal Pradesh and Jammu and Kashmir into Pakistan. Option d (Ravi) again is a tributary of the Indus, rising in Himachal Pradesh and not in Nepal. None of these rivers originates in Nepal to join the Ganga, so they do not fit the question.

Common Pitfalls:
Students sometimes mix up Himalayan river systems and confuse the tributaries of the Ganga with those of the Indus. Another common error is to remember only the nickname like “Sorrow of Bihar” but not link it to Kosi and its Nepalese origin. To avoid confusion, it helps to group rivers mentally as “Ganga basin” versus “Indus basin” and to associate Kosi explicitly with Nepal and Bihar.

Final Answer:
The river that originates in Nepal and flows into the Ganges is the Kosi.