Read the following statements carefully and select the correct option.
A. Guard cells are living, having nucleus and chloroplast.
B. The outer wall of guard cells is thick and elastic.
C. The stomatal aperture, guard cells and subsidiary cells together called stomatal apparatus.

• A

  Only (A)

• B

  (B) and (C)

• C

  (A) and (C)

• D

  (A),(B) and (C)