The cutting of forests leads to

Answer: (a) Soil erosion and uncontrollable floods

Without trees, rain hits the soil directly, runs off fast and carries soil away — floods and erosion follow.

The idea

A forest handles rain in three ways. Leaves break the fall of raindrops. The litter on the ground soaks up water like a sponge. Roots hold the soil. Remove the trees and rain hits bare ground and runs straight off, taking the soil with it.

Trees are cut → Rain runs off fast → Topsoil is washed into rivers → Silt raises the river bed → The river overflows: floods

Why the others are wrong

(b) Deforestation causes SILTING of rivers, not de-silting.

(c) Losing forests tends to reduce rainfall and humidity (less transpiration).

The trap

(b) flips silting into de-silting.

Also know

Forests also return water to the air through their leaves, so clearing them tends to make the local climate drier. The Chipko movement’s slogan said it simply: forests bear soil, water and pure air.