The correct answer is option 'A', Nepal Himalayas.

The Himalayas are a vast mountain range that stretches across several countries in South Asia, including Nepal, India, China, Bhutan, and Pakistan. It is the highest and most extensive mountain range in the world. The Himalayas are divided into several regions, each with its own unique characteristics.

Among these regions, the Nepal Himalayas have the maximum stretch from east to west. Let's explore why this is the case:

1. Nepal Himalayas:
The Nepal Himalayas refer to the section of the Himalayan range that lies within the borders of Nepal. It is the central region of the Himalayas and is known for its majestic peaks, including Mount Everest, the highest peak in the world.

2. Stretch from East to West:
The Nepal Himalayas have a significant east-west stretch compared to other parts of the Himalayas. This means that the mountain range extends over a greater distance from east to west in Nepal than in other regions.

3. Geographical Features:
The Nepal Himalayas are characterized by deep valleys, towering peaks, and vast glaciers. The region is home to eight of the world's fourteen highest peaks, including Mount Everest, Kanchenjunga, and Makalu. The diverse landscape of the Nepal Himalayas attracts numerous trekkers and mountaineers from around the world.

4. Impact on Climate and Biodiversity:
The east-west stretch of the Nepal Himalayas has a significant impact on the climate and biodiversity of the region. The mountains act as a barrier, blocking the monsoon winds from the Indian subcontinent and creating a rain shadow effect. This results in varying climatic conditions and vegetation patterns across the region. The Nepal Himalayas house a wide range of flora and fauna, including unique species adapted to the high-altitude environment.

5. Cultural Significance:
The Nepal Himalayas hold immense cultural significance for the people of Nepal. The region is home to various ethnic groups, each with its own distinct traditions, languages, and lifestyles. The Sherpas, who live in the high-altitude areas of the Nepal Himalayas, are renowned for their mountaineering skills and have played a crucial role in supporting expeditions to the highest peaks.

In conclusion, the Nepal Himalayas have the maximum stretch from east to west compared to other parts of the Himalayan range. This region is known for its breathtaking mountain scenery, diverse ecosystems, and rich cultural heritage.