Which of the following is an incorrect pair?

Which processes were included in the integrated organic farming by Ramesh Chandra Dagar,a farmer from Sonipat,Haryana?
$I-$ Bee-keeping
$II-$ Dairy management
$III-$ Water harvesting
$IV-$ Composting
$V-$ Chemical fertilizers
$VI-$ Chemical pesticides

Domestic sewage mainly contains $A$ wastes which are readily decomposed with the help of $B$. Here $A$ and $B$ refer to:

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 $0.05\ ppm$.

The Chernobyl tragedy occurred in

Polyblend is made using $..............$.