The correct answer is: b) Floods & landslides.
Heavy rainfall in Arunachal Pradesh can lead to floods and landslides. The state is located in the Himalayas, which are a mountain range that is prone to landslides. When it rains heavily, the soil becomes saturated and can no longer support the weight of the trees and rocks on top of it. This can cause landslides, which can block roads and railways, damage property, and even kill people.
Floods can also occur when it rains heavily. The rainwater can cause rivers to overflow their banks, flooding towns and villages. Floods can damage property, crops, and infrastructure. They can also cause people to lose their lives.
The other options are incorrect. Droughts are caused by a lack of rainfall, not an excess of it. Dust storms are more common in dry, arid regions, not in mountainous regions like Arunachal Pradesh. Heatwaves are also more common in dry, arid regions.