At the end of the winter they are most numerous in fresh water. they will cover surface of aquatic plants or poles and wooden borders of ponds. If you like to study them you can scrape the brown growth with a flat piece of plastic. you can also use a sponge. for the free living (plankton) species fine mesh plankton net is very useful.
C. There is a storm ?
Warm air rises and cold air drops because cold air is denser so when the warm air rises it when it collides with the cold air then comes condensation and clouds start to form and a storm can occur
The answer is (b). I think
Decrease in the tree population can damage the environment.
Water is an important transport and reaction medium
hope this helps :)
