The $UN$ Conference of Parties on climate change in the year $2011$ was held in

Assertion: Eutrophication shows an increase in productivity in water.
Reason: With increasing eutrophication,the diversity of the phytoplankton increases.

Identify the odd one out.

What do '$X$','$Y$',and '$Z$' represent in the given figure respectively?

Biological magnification refers to

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