Solution

Replum is the frame-like placenta, across which the septum stretches, from which the valves of a capsule or other dehiscent fruit fall away in dehiscence, as in Cruciferae, certain Papaveraceae, Mimosa, etc. sometimes incorrectly applied to the septum. The fruit of Cruciferae is a peculiar kind of capsule named siliqua. It opens by two valves, which are the modified carpels, leaving the seeds attached to a framework made up of the placenta and tissue from the junction between the valves (replum). In Cruciferae, ovary is unilocular but becomes bilocular due to development of false septum called as replum. So, the special feature of the ovary in Cruciferae is false septum. Hypogyny, polyandry and one row of ovules on each placenta are absent in Cruciferae.
Therefore, the correct answer is option C.