Which of the following statements is incorrect regarding $DDT$?

For the best ecological balance,what percentage of the land mass of a country in the plains should be covered with forests (in $, \%$)?

Which one of the following pairs is not correctly matched?

$UV$ radiation from the sun causes which of the following eye disorders?

The Ministry of Environment and Forest has initiated the Ganga Action Plan and Yamuna Action Plan:
$(i)$ To save these major rivers of our country from pollution.
$(ii)$ It is proposed to build a large number of sewage treatment plants.
$(iii)$ Under these plans,only treated sewage may be discharged into the rivers.

Assertion : Methane,a component of greenhouse gases,contributes about $20$ percent to global warming.
Reason : The introduction of multi-point fuel injection engines in automobiles has decreased methane content in the exhausts.