To which habitat is the elephant adapted?

Ecological equivalents refer to:

Behavioural adaptations to the environment in desert lizards are:
$I.$ Burrowing into the soil
$II.$ Losing heat during high temperature
$III.$ Active during morning and evening
$IV.$ Insulating body due to thick fatty dermis
Select the correct pair.

In summer,when the outside temperature is higher than our body temperature,we sweat profusely. The resulting evaporative cooling,similar to what happens with a desert cooler in operation,brings down the body temperature. In winter,when the temperature is much lower than $37^{\circ}C$,we start to shiver,a kind of exercise which produces heat and raises the body temperature. These organisms are called:

Distinguish between the following:
$(a)$ Hibernation and Aestivation
$(b)$ Ectotherms and Endotherms

Which biome is associated with the Arctic desert?