In which of the following families is parietal placentation present?

Placentation refers to the arrangement of ovules on the placenta inside the ovary of a flower. Botanists classify it by where the placenta forms: marginal (along a single ventral suture), axile (on a central axis in a multilocular ovary), parietal (on the inner ovary wall of a unilocular ovary), free central (on a central column with no septa), or basal (at the base of the ovary).

Brassicaceae (the mustard family) has a bicarpellary, syncarpous ovary that starts out unilocular, with two parietal placentae running along the fused margins of the two carpels. As the ovary matures, a thin false septum grows between these two placentae, splitting the cavity into two chambers; the placental margins together with the septum's supporting frame form the persistent structure called the replum. Because the ovules remain attached along these placentae on the ovary wall — never shifting onto a fused central axis — the placentation is still classified as parietal even though the ovary becomes secondarily bilocular.

• Malvaceae: a multilocular, syncarpous ovary with ovules borne on a central axis — axile placentation.

• Asteraceae: a unilocular ovary with a single ovule attached at its base — basal placentation.

• Solanaceae: a bicarpellary, syncarpous, multilocular ovary with ovules on a central axis — axile placentation.

Since only Brassicaceae shows ovules attached to the ovary wall of a unilocular chamber, it is the family with parietal placentation among the options given.