Answer :
Debris flow is the mass wasting feature that primarily operates in areas of steep terrain and wet conditions, capable of rapid movement and potentially causing great damage. So, the correct answer is option 4) Debris flow.
Among the mass wasting features listed, debris flow operates primarily in areas of steep terrain and wet conditions. Debris flow is a rapid flow of saturated debris, typically including a mixture of water, soil, rock, organic matter, and other materials, all moving downslope under the force of gravity. It can occur in response to heavy rainfall, rapid snowmelt, or volcanic activity, which adds water to the soil and rock, increasing its weight and acting as a lubricant that weakens the cohesive forces between particles.
Debris flow is considered one of the most dangerous forms of mass wasting because it can happen suddenly, often with little warning, and because the flow can move at high speeds and with enough force to destroy structures and transport large boulders and trees. So, the correct answer is option 4) Debris flow.
