Som River: A Tributary of the Mahi River

The question asks to identify the major river of which the Som River is a tributary. A tributary is a stream or river that flows into a larger stream or river, known as the main stem or trunk river. Tributaries do not flow directly into a sea or ocean.

Identifying the Som River's Parent River

The Som River originates in the Udaipur district of Rajasthan, India. It is a significant river in the region, known for its contribution to the local water resources.

• Correct Identification: The Som River is a well-known tributary of the Mahi River. The confluence of the Som and Mahi rivers is an important geographical feature in the Banswara district of Rajasthan. The Mahi River itself flows through Rajasthan and Gujarat before emptying into the Arabian Sea.

Evaluating Other Options

Let's look at why the other options are not correct:

• Sabarmati River: The Sabarmati River is another important river in western India, flowing through Rajasthan and Gujarat. It is an independent river system and does not have the Som River as its tributary. Its main tributaries include the Watrak River.
• Banas River: The Banas River is a tributary of the Chambal River, which in turn is a tributary of the Yamuna River. The Som River does not flow into the Banas River.
• Luni River: The Luni River is the largest river in the desert region of Rajasthan. It flows into the Rann of Kutch in Gujarat and does not have the Som River as its tributary.

Therefore, based on geographical facts, the Som River flows into the Mahi River, making the Mahi River its parent river.