Explanation
The correct answer is B: Pea.
Marginal placentation is a type of placentation where the ovules are attached to the margin or the edge of the ovary. In pea plants, the ovary is unilocular (has one compartment) and the ovules are attached to the upper margin of the ovary. This type of placentation is also known as parietal placentation.
In tomato plants, the ovary is divided into several compartments and the ovules are attached to a central axis, which is an example of axial placentation.
In mustard plants, the ovary is also divided into several compartments, but the ovules are attached to a central column that projects inward from the walls of the ovary, which is an example of free central placentation.
In sunflower plants, the ovary is inferior (below the attachment of other floral parts) and the ovules are attached to a central column that extends from the base of the ovary to the top, which is an example of basal placentation.
