Match the following in Column $I$ with the means adopted to tide over periods of unfavorable conditions in Column $II$.

$i$. Birds	$c$. Migration
$ii$. Seeds	$a$. Dormancy
$iii$. Snails	$d$. Aestivation
$iv$. Polar bear	$b$. Hibernation

Small animals have a larger surface area relative to their volume,so they tend to lose body heat very fast when it is cold outside. Then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in polar regions. Which of the following explains why small animals are more easily able to climb up a rock compared to large animals?

Which one of the following pairs is correctly matched?

$I.$ Many xerophytic plants have thick cuticle on leaf epidermis and sunken stomata.
$II.$ Some xerophytic plants have a special photosynthetic pathway $(CAM)$ that enables their stomata to close during the day.
$III.$ $Opuntia$ has spines (modified leaves) and a photosynthetic phylloclade (stem).
$IV.$ All adaptations are genetically fixed in all organisms.
Choose the combination of correct statements.

Plains with snow,ice,and frozen soil for most of the year are found in

Populations of different species living together in a common habitat form which of the following?