The correct answer is option 2: 1 and 3.

The Western Ghats and the Eastern Himalayas are considered to be biodiversity hotspots.

1. Western Ghats: The Western Ghats are a mountain range that runs parallel to the western coast of India. They are home to a rich variety of plant and animal species, many of which are unique to this region. This area is known for its dense forests, rivers, and waterfalls, which provide a diverse range of habitats for wildlife. The Western Ghats have been recognized as a UNESCO World Heritage Site and are considered one of the eight hottest hotspots for biological diversity in the world.

2. Aravalli Hills: The Aravalli Hills are a range of mountains in western India, mainly in the state of Rajasthan. While these hills have important ecological value, they are not considered a biodiversity hotspot.

3. Eastern Himalayas: The Eastern Himalayas are located in northeastern India and are known for their incredible biodiversity. This region is home to a wide range of plant and animal species, including many endangered and endemic species. The Eastern Himalayas are considered one of the global biodiversity hotspots due to their high levels of species richness and endemism.