Rice fields produce an important greenhouse gas. Name it.

In the town of Arcata,the local people,in collaboration with biologists from $...........$,developed an integrated wastewater treatment process within a natural system.

What is the full form of $NGO$?

$A$ - $BOD$ is a measure of the organic matter present in the water.
$R$ - The lower the $BOD$ of water,the lower is its polluting potential.

Provide the full names for the following abbreviations:
$(i)$ $HFC$
$(ii)$ $CFC$

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 $0.05\ ppm$.