The correct option is D maize
Mustard, gram, and soya bean are dicot plants.
Maize is a monocot plant. In monocots, the mesophyll of the leaf is not differentiated into palisade and spongy parenchyma, unlike the dicot leaf.
Palisade parenchyma is made up of elongated cells that are arranged vertically and are parallel to each other. They are present along the adaxial epidermis.
Spongy parenchyma is made up of oval or round cells with a lot of intercellular spaces and air cavities between them. It is present below palisade parenchyma cells.