What is the shape of the two guard cells which enclose stomata?

a. Oval

b. Triangular

c. Rectangular

d. Kidney shaped

The guard cells that enclose stomata differ slightly in shape depending on the plant type:

• In dicot plants, guard cells are kidney-shaped.
• In monocot plants (like grasses), they are usually dumbbell-shaped.

Since the question is general, the expected correct answer is:

The correct answer is d. Kidney shaped