Why do mammals of colder regions generally have shorter ears and limbs?
$I.$ To minimize their surface area to volume ratio
$II.$ To minimize heat loss
$III.$ To maximize their surface area to volume ratio
$IV.$ To maximize heat loss
Choose the correct combination from the given options:

• A
  $I$ and $II$
• B
  $II$ and $III$
• C
  $III$ and $IV$
• D
  $I$ and $IV$