Answer :

• c)
  Arunachal Pradesh

The correct answer is option C, Arunachal Pradesh.

Arunachal Pradesh is a state located in the northeastern part of India. It is known for its rich biodiversity and dense forests. Here are the reasons why Arunachal Pradesh has the thickest forest among the given options:

1. Geographic Location:
Arunachal Pradesh is situated in the eastern Himalayas, which is known for its dense vegetation. The state shares its borders with Bhutan, China, and Myanmar, and is surrounded by the Himalayan mountain range. The geographical location and favorable climate contribute to the growth of thick forests in the region.

2. Altitude and Topography:
Arunachal Pradesh has a varied topography with high mountains, deep valleys, and wide plains. The state's altitude ranges from 50 meters to over 7,000 meters above sea level. This variation in altitude creates different microclimates and habitats, leading to the growth of diverse flora and fauna.

3. Rainfall and Climate:
Arunachal Pradesh receives heavy rainfall throughout the year, especially during the monsoon season. The average annual rainfall in the state is around 3,000 to 4,000 millimeters. The high amount of rainfall combined with the region's favorable climate provides ideal conditions for the growth of dense forests.

4. Biodiversity:
Arunachal Pradesh is considered a biodiversity hotspot due to its rich flora and fauna. The state is home to numerous endangered species, including the Bengal tiger, clouded leopard, and red panda. The dense forests of Arunachal Pradesh provide a habitat for these species, making it a crucial ecosystem for their survival.

5. Protected Areas:
Arunachal Pradesh has several protected areas, national parks, and wildlife sanctuaries that contribute to the conservation of its forests. These include Namdapha National Park, Dibang Wildlife Sanctuary, and Pakhui Tiger Reserve. These protected areas help in preserving the natural habitat and maintaining the ecological balance of the region.

In conclusion, Arunachal Pradesh has the thickest forest among the given options due to its favorable geographical location, varied topography, heavy rainfall, rich biodiversity, and the presence of protected areas. The state's forests not only provide a home for numerous species but also contribute to the overall ecological health of the region.