The correct option is D Bean-shaped guard cells
Monocot leaves are also called isobilateral leaves as its both surfaces are similar. It has parallel venation as the veins are arranged parallel to one another. An equal number of stomata are present on both sides of the leaf, called an amphistomatic leaf. Bulliform cells are large, empty, colorless cells present in the adaxial epidermis that absorbs water and becomes turgid when the leaf surface is exposed. They help in the rolling and unrolling of leaves - due to changes/variations in turgidity. Guard cells are dumbbell-shaped in monocots.
The guard cells are bean-shaped in dicot leaves.