The correct answer is (a) Arunachal Pradesh.
Arunachal Pradesh has the largest percentage of its area under forest cover, with 77.9% of its land area covered by forests. This is followed by Mizoram (75.3%), Nagaland (74.4%), and Meghalaya (71.4%).
The high forest cover in these states is due to a number of factors, including their mountainous terrain, which makes it difficult to cultivate land, and their low population density. The forests in these states are also home to a variety of plant and animal species, many of which are found nowhere else in the world.
The forest cover in these states plays an important role in the environment, providing a habitat for wildlife, regulating the climate, and preventing soil erosion. It also plays an important role in the economy of these states, providing employment for many people and supporting a number of industries, such as tourism and agriculture.
However, the forests in these states are facing a number of threats, including deforestation, mining, and development. These threats are having a negative impact on the environment and the economy of these states. It is important to protect the forests in these states in order to ensure the long-term sustainability of the environment and the economy.