Observe the diagr

a) These types of guard cells are found in dicots because as we know the shape is bean shaped. Whereas for monocots, it is usually dumble-shaped.

b) Higher water content is shown in figure (i) because as we can see in that figure the guard cells are showing turgidity and the stoma is open carrying out transpiration as well as photosynthesis.

c) The element that plays an important role in the opening and closing of stomata is potassium ion. Potassium is responsible for the k+ or malate ion hypothesis. In short in this theory, the change in turgor pressure of the guard cells which is responsible for opening and closing of the stomata results in absorption andloss of K+ ions by guard cells.