Which of the following rivers of India is classified as a Trans Himalayan river because it originates beyond the main Himalayan ranges and then flows through them into the Indian subcontinent?

Introduction / Context:
This question belongs to physical geography and focuses on the classification of Indian rivers based on their origin and course. Trans Himalayan rivers are those that originate beyond the Himalayas, usually on the Tibetan plateau, and then flow through deep gorges in the Himalayan ranges before entering India. Identifying such rivers helps in understanding regional hydrology and river system classification.

Given Data / Assumptions:

• The question asks for a Trans Himalayan river among the given options.
• The listed rivers are Ganga, Yamuna, Indus, and Ravi.
• We use standard geographical classifications of Indian river systems.

Concept / Approach:
Indian rivers are broadly classified as Himalayan rivers, Peninsular rivers, and Trans Himalayan rivers. Trans Himalayan rivers such as Indus, Satluj, and Brahmaputra originate beyond the main Himalayan range, often in Tibet, and then cross the Himalayas to enter India. The Ganga and Yamuna are snow fed Himalayan rivers that originate in the Indian Himalayas, while Ravi is part of the Indus system but originates in the Himalayas rather than beyond them. Among the given options, Indus is the classic example of a Trans Himalayan river.

Step-by-Step Solution:
Step 1: Recall the origin of the Indus River. Indus originates in the region of Tibet, near Lake Mansarovar, beyond the main Himalayan ranges. Step 2: Note that after its origin, the Indus flows through deep gorges in the Himalayas to enter the Ladakh region of India. Step 3: This pattern of originating beyond the Himalayas and then crossing them qualifies Indus as a Trans Himalayan river. Step 4: Ganga originates at the Gangotri glacier in the Indian Himalayas and is therefore a Himalayan river, not Trans Himalayan. Step 5: Yamuna originates from the Yamunotri glacier, also within the Indian Himalayas. Step 6: Ravi originates in the Himalayas and is part of the Indus system but does not originate beyond the Himalayas. Step 7: Therefore, among the options, Indus is the correct Trans Himalayan river.

Verification / Alternative check:
Standard geography references list Indus, Satluj, and Brahmaputra as the main Trans Himalayan rivers. All three rivers rise on or near the Tibetan plateau and cut through the Himalayas to enter India. Since Satluj and Brahmaputra are not in the given options, and Ganga, Yamuna, and Ravi are Himalayan but not Trans Himalayan in origin, this confirms that Indus is the only correct choice.

Why Other Options Are Wrong:
Option A, Ganga, is a major Himalayan river but not a Trans Himalayan one because it originates at the Gangotri glacier within the Himalayas. Option B, Yamuna, similarly originates from the Yamunotri glacier in the Himalayas and is a tributary of the Ganga. Option D, Ravi, is also a Himalayan river and flows through the states of Himachal Pradesh and Punjab, but it does not originate beyond the Himalayan range. Only option C, Indus, fits the Trans Himalayan category.

Common Pitfalls:
A frequent mistake is to assume that any river associated with the Himalayas is automatically Trans Himalayan, which is not correct. The key feature of a Trans Himalayan river is that it originates beyond the main Himalayan range, often in Tibet. Remembering the specific origins of major rivers like Ganga, Yamuna, Indus, and Brahmaputra helps avoid confusion and answer such questions accurately.

Final Answer:
The river that is classified as a Trans Himalayan river is the Indus.