Succulent xerophytes are likely to be found in

$A$ regulators are able to maintain homeostasis by means which ensure constant body temperature,constant osmotic concentration,etc. All $B$ and $C$ and a very few lower vertebrate and invertebrate species are indeed capable of such regulation (thermoregulation and osmoregulation).
Evolutionary biologists believe that the 'success' of mammals is largely due to their ability to maintain a constant body $D$ and thrive whether they live in Antarctica or in the Sahara desert.
Choose the correct option for $A, B, C$ and $D$.

Deserts occur in areas of

Chaparral occurs in which area?

In most animals,the metabolic reactions proceed in a $A$ temperature range (in humans,it is $37^{\circ} C$). But there are microbes (archaebacteria) that flourish in hot springs and deep sea hydrothermal vents where temperatures far exceed $B$. Choose the correct option for $A$ and $B$.

$A$ population characteristic of a species susceptible to extinction is