Which of the following features distinguishes the Purvanchal hills from the rest of the Himalayan mountain system?

The correct option is: They stretch in a convex arc along the eastern frontier.

Explanation:

The Purvanchal range, or the Eastern Hills, forms the easternmost extension of the Himalayan mountain system running along India's eastern border. These hills bend sharply to the south beyond the Dihang gorge and stretch along the eastern frontier of India in a convex arc.

Let's analyze why the other options are incorrect:

• "They include the Aravalli and Satpura hill groups": The Aravalli and Satpura ranges are located in central and western Peninsular India, completely separate from the Himalayan system.

• "They are snow-covered throughout the year": Unlike the Greater Himalayas (Himadri), the Purvanchal hills are composed of medium-height hills (such as the Patkai, Naga, Mizo, and Manipur hills) covered with dense forests rather than perennial snow cover.

• "They form the highest peaks of the Zanskar range": The Zanskar range is situated in the Trans-Himalayan region of Jammu & Kashmir and Ladakh, far from the Purvanchal hills in northeastern India.