The monsoon season in Nagaland brings a high risk of:

Avalanches
Flooding
Wildfires
Sandstorms

The correct answer is: b) Flooding.

The monsoon season in Nagaland brings a high risk of flooding. The monsoon rains are heavy and can cause rivers to overflow their banks, leading to flooding in low-lying areas. The flooding can damage homes and businesses, and can also lead to landslides.

Avalanche is a large mass of snow and ice that falls down a mountain. Avalanches are most common in the winter and spring, when the snow is heavy and wet. They can be very dangerous, and can cause serious injuries or death.

Wildfire is a large, uncontrolled fire that burns in forests, grasslands, or other areas of natural vegetation. Wildfires can be caused by lightning strikes, human activity, or even spontaneous combustion. They can be very destructive, and can cause loss of life, property, and wildlife.

Sandstorm is a large cloud of sand and dust that is blown by the wind. Sandstorms can be very dangerous, and can cause respiratory problems, skin irritation, and eye problems. They can also damage property and infrastructure.