Which of the following is a major factor for desertification?

The Haryana Kisan Kalyan Club was created by $..........$.

Choose the correct option regarding the following statements:
$(1)$ $CO_2$ contribution in global warming is $60\%$.
$(2)$ Greenhouse effect occurs due to deforestation.
$(3)$ Due to the greenhouse effect,the present average temperature at the surface of the Earth is $15^oC$.
$(4)$ The amount of $DDT$ in small fish is $0.05\ ppm$.

Lead $(Pb)$ causes:

In this soil conservation method,several grasses are left out in the soil after the crop is harvested.

In an ecological crisis,whose interference plays an important role?