The correct answer is option 'D' - Aravalli Range.

The Aravalli Range is a mountain range located in western India and is the oldest mountain range in the country. It stretches approximately 692 km in a northeastern direction across the states of Gujarat, Rajasthan, Haryana, and Delhi. The range acts as a barrier for the wind carrying rain to reach the Thar Desert.

Here's how the Aravalli Range blocks the wind carrying rain:

1. Importance of Rain for the Thar Desert:
Rainfall is crucial for the Thar Desert as it is a hot and arid region with limited water resources. The desert receives most of its rainfall during the monsoon season, which is from June to September. The rainwater is essential for sustaining the desert ecosystem and supporting agriculture and livelihoods in the region.

2. Location of the Aravalli Range:
The Aravalli Range runs across the western part of India and acts as a barrier between the Thar Desert and the Arabian Sea. The range runs parallel to the western coastline, preventing the moisture-laden winds from the Arabian Sea from reaching the desert.

3. Orographic Effect:
The Aravalli Range causes an orographic effect, which is the process by which mountains block the passage of moist air, forcing it to rise and cool. As the air rises, it loses its moisture in the form of rain or snow on the windward side of the mountains. This results in a rain shadow effect on the leeward side, which in this case is the Thar Desert.

4. Blocking of Southwest Monsoon:
During the monsoon season, the prevailing winds in India are the southwest monsoon winds. These winds bring moisture from the Arabian Sea and carry rainfall to various parts of the country. However, when these winds encounter the Aravalli Range, they are forced to rise and lose their moisture. As a result, the Thar Desert receives significantly less rainfall compared to the windward side of the mountains.

In conclusion, the Aravalli Range acts as a natural barrier that blocks the wind carrying rain from reaching the Thar Desert. This phenomenon, known as the orographic effect, leads to the arid conditions in the desert region.