The correct option is C both a and b The anatomy of a leaf shows the presence of mesophyll cells between the upper and lower epidermis. In a dicot leaf, the mesophyll cells are differentiated into palisade parenchyma (on the adaxial or upper side) and spongy parenchyma (on the abaxial or lower side). In order to reduce the rate of transpiration, the stomata is located on the lower side of the leaves. The upper and the lower side of the dicot leaf are different from each other. Thus they are called dorsiventral leaf or bi-facial leaf.
An isobilateral leaf as seen in the monocots, shows the mesophyll tissue to be made up of only spongy parenchyma and there is equal distribution of stomata on both the upper and lower epidermis.