In desert grasslands,which type of animals are relatively more abundant?

Which of the following areas are used as habitats by organisms?
$I -$ Scorching deserts
$II -$ Rain-soaked rainforests
$III -$ Rushing streams
$IV -$ Deep ocean trenches
$V -$ Polar regions
$VI -$ High mountain tops
$VII -$ Thermal springs
$VIII -$ Stinking compost pits
$IX -$ Our intestine

Many freshwater animals cannot live for long in sea water and vice-versa mainly because of the

What is a tree line?

Give an example for:
$(a)$ An endothermic animal
$(b)$ An ectothermic animal
$(c)$ An organism of benthic zone

Succulent xerophytes are likely to be found in