Which of the following rivers originates in Nepal and then flows into the Ganga river system in India?

Introduction / Context:
Many of the major rivers in the northern part of the Indian subcontinent rise in the Himalayas and flow through more than one country. Some start in Nepal and then enter India to join the Ganga, while others belong to the Indus system and flow through different regions. This question tests whether the learner can correctly identify which river among the options starts in Nepal and then becomes part of the Ganga river system.

Given Data / Assumptions:

The river must have its origin in Nepal.

It must flow into India and join the Ganga river system.

The options are Kosi, Jhelum, Chenab and Ravi.

We assume the commonly accepted courses of these rivers.

Concept / Approach:
The Kosi river is a well known Himalayan river that rises in Tibet and Nepal, then flows through eastern Nepal before entering Bihar in India, where it joins the Ganga. It is popularly known as the sorrow of Bihar because of frequent floods. By contrast, Jhelum, Chenab and Ravi are part of the Indus river system, flowing mainly through Jammu and Kashmir and Punjab before entering Pakistan. Therefore, the correct approach is to identify Kosi as the Nepal originating river that becomes a tributary of the Ganga in India.

Step-by-Step Solution:
Step 1: Recall that the Kosi river flows from the Himalayas in Tibet and Nepal into the Indian state of Bihar.Step 2: Remember that once in Bihar, Kosi joins the Ganga, making it a Himalayan tributary of the Ganga.Step 3: Note that Jhelum, Chenab and Ravi are all rivers of the Indus basin and flow primarily through Jammu and Kashmir and Punjab into Pakistan.Step 4: Conclude that only Kosi fits the condition of originating in Nepal and flowing into the Ganga system.

Verification / Alternative check:
Consulting an atlas or river basin map shows Kosi flowing from Nepal into Bihar and joining the Ganga near Kursela. It is clearly labelled as part of the Ganga basin. On the same map, Jhelum, Chenab and Ravi are connected to the Indus river, not to the Ganga. This confirms that Kosi, and not the other options, satisfies both parts of the question: origin in Nepal and confluence with the Ganga in India.

Why Other Options Are Wrong:
Jhelum originates in the Kashmir Valley and flows into Pakistan, joining the Chenab and then the Indus, not the Ganga.
Chenab rises in the upper Himalayas in Himachal Pradesh and the Jammu region and is a major tributary of the Indus, not a tributary of the Ganga.
Ravi also originates in the Himalayas in Himachal Pradesh and flows into Pakistan to join the Chenab and Indus system, not the Ganga.
None of these rivers both originate in Nepal and join the Ganga in India.

Common Pitfalls:
Candidates sometimes mix rivers of the Indus and Ganga systems because they all arise in the Himalayas. Another source of confusion is that several Himalayan tributaries cross international borders, so it is important to remember which ones pass through Nepal. A simple memory aid is to link Kosi with Bihar floods and Nepal s eastern Himalayas, while associating Jhelum, Chenab and Ravi with the Indus basin and with Jammu and Kashmir and Punjab rather than Nepal.

Final Answer:
The river that originates in Nepal and then flows into the Ganga river system in India is the Kosi.