Which part of the world has a high density of organisms?

The variation shown by the medicinal plant $Rauwolfia \text{ } vomitoria$ growing in different Himalayan ranges represents:

The largely tropical ............. rain forest in South America has the greatest biodiversity on earth.

In India,temperate evergreen vegetation occurs mostly in

$X$ - India has $2.4\%$ of the world's land area.
$Y$ - The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution.
$Z$ - Species-area relationships were given by Alexander von Humboldt.
Identify the truth value of $X, Y,$ and $Z$ respectively.

In India,tropical evergreen forests occur in