Which one of the following rivers is classified as an international river because it flows through more than one country before reaching the sea?

Introduction / Context:
Rivers can be classified as national or international depending on whether they flow entirely within one country or pass through more than one sovereign state. International rivers often require cooperation between countries for water sharing, navigation, and flood control. In the South Asian context, there are several rivers that cross national borders. This question asks which river among the options is considered an international river because it flows through more than one country.

Given Data / Assumptions:

• The options are Brahmaputra, Cauvery, Krishna, Narmada, and Mahanadi.
• A river is considered international if it flows through the territory of at least two countries.
• The focus is on the main course of the river, not on minor tributaries.
• We assume standard school level knowledge of major Indian river systems.

Concept / Approach:
The Brahmaputra is a major river of Asia that flows through several countries. It originates in the Tibet region of China, where it is known as the Yarlung Tsangpo, then enters India through Arunachal Pradesh and flows through Assam, and finally enters Bangladesh, where it merges with the Ganga system before emptying into the Bay of Bengal. Because it crosses international boundaries and is shared by multiple countries, Brahmaputra is clearly an international river. In contrast, the Cauvery, Krishna, Narmada, and Mahanadi rivers flow mainly within India without passing into another sovereign country.

Step-by-Step Solution:
Step 1: Recall the course of the Brahmaputra river, beginning in Tibet, flowing through India, and ending in Bangladesh.Step 2: Recognise that this path crosses the borders of at least three different countries.Step 3: Consider the other rivers listed. Cauvery rises in Karnataka and flows through Tamil Nadu before entering the sea within India.Step 4: Krishna flows across states like Maharashtra, Karnataka, Telangana, and Andhra Pradesh but remains entirely within India.Step 5: Narmada and Mahanadi also flow entirely within Indian territory.Step 6: Conclude that Brahmaputra is the only river among the options that qualifies as an international river.

Verification / Alternative check:
Maps of South Asia and Indian geography texts routinely show the route of the Brahmaputra across China, India, and Bangladesh. These sources also describe water sharing and flood management agreements related to Brahmaputra and the greater Ganga Brahmaputra Meghna system. No similar international boundary crossing is associated with the Cauvery, Krishna, Narmada, or Mahanadi. This confirms that Brahmaputra is correctly classified as an international river among the options.

Why Other Options Are Wrong:
Cauvery is a peninsular river confined to southern India and is the subject of inter state river water disputes, not international disputes. Krishna is another major peninsular river that flows only within India, despite crossing several state boundaries. Narmada flows through central India and empties into the Arabian Sea without entering any other country. Mahanadi flows through states like Chhattisgarh and Odisha but does not leave Indian territory. Therefore, none of these rivers meet the definition of international river used in this question.

Common Pitfalls:
Some students confuse inter state rivers with international rivers because both require cooperative agreements. For example, Cauvery is well known for water sharing disputes between Indian states, but it is not shared between countries. To avoid confusion, it is important to distinguish between rivers that cross internal state boundaries and those that cross international borders between sovereign nations.

Final Answer:
Brahmaputra is an international river because it flows through China, India, and Bangladesh before reaching the sea.