Weathering as a pre-requisite for mass movement:
- Weathering refers to the process of breaking down and disintegration of rocks and minerals at or near the Earth's surface.
- It can occur through physical, chemical, and biological processes.
- Weathering weakens the rocks and makes them more susceptible to mass movement.
- The disintegration of rocks due to weathering creates loose debris and soil, which can easily be transported by mass movement processes.
- Therefore, weathering is a pre-requisite for mass movement as it provides the loose material that can be moved downslope.

Debris avalanche as a characteristic of humid regions:
- A debris avalanche is a type of mass movement in which a large volume of loose rock, soil, and debris rapidly moves down a slope.
- This movement is often triggered by earthquakes, volcanic eruptions, heavy rainfall, or other factors that destabilize the slope.
- While debris avalanches can occur in any region, they are more commonly associated with steep slopes in humid regions.
- In humid regions, heavy rainfall can saturate the soil and increase its weight, leading to increased instability of slopes.
- The presence of vegetation in humid regions can also contribute to slope instability as plant roots can weaken the soil and provide pathways for water infiltration.
- Additionally, the presence of clay-rich soils in humid regions can contribute to the occurrence of debris avalanches as clay particles can become lubricated when wet, reducing friction and allowing the material to flow more easily.

Correct statement:
- The correct statement is option 'B' - 2 only.
- Weathering is a pre-requisite for mass movement as it provides the loose material that can be moved downslope.
- However, debris avalanches are not exclusively characteristic of humid regions.
- While they are more commonly associated with steep slopes in humid regions due to factors like heavy rainfall and soil saturation, they can occur in any region where the conditions for mass movement are present.

Conclusion:
- In conclusion, weathering is a pre-requisite for mass movement as it provides the loose material necessary for movement.
- However, debris avalanches are not limited to humid regions and can occur in any region where the conditions for mass movement are present.