$I.$ 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.

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