What is the full form of $NGO$?

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

What is $FOAM$?

At the beginning of the twentieth century,forests covered about ....... of the land of India. By the end of the century,it shrunk to.......

Which energy source does not release $CO_2$?

$A$ lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this.
$A.$ Lots of urea and phosphate fertilizer were used in the crops in the vicinity.
$B.$ The area was sprayed with $DDT$ by an aircraft.
$C.$ The lake water turned green and stinky.
$D.$ Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis.
Which two of the above were the main causes of fish mortality in the lake?