Thin-walled passage cells are found in:

• A
  The region of the style through which the pollen tube grows towards the ovule.
• B
  The endodermis of roots,facilitating the rapid transport of water from the cortex to the pericycle.
• C
  The elements of the phloem that act as entry points for substances being transported to other parts of the plant.
• D
  The seed coat during germination,allowing the embryonic axis to develop.