The correct option is D Achlamydeous flowers
Cyathium inflorescence shows the presence of achlamydeous flowers. Achlamydeous flowers are flowers without a perianth. The cyathia are sometimes solitary, but are usually in cymes, inflorescences of the second order, in pseudumbels, on dichotomously branched stalks or in so-called simple cymes which consist of one central and two lateral cyathia.The showy, red, modified leaves of these plants are not petals. In fact, they are not even part of the true flowers. They surround clusters of small, greenish, cup-shaped structures called cyathia. Each cyathium is actually a flower cluster or inflorescence containing unisexual, apetalous male and female flowers. The inconspicuous male flowers occur in clusters and are reduced to a single red stamen, while the female flower consists of a single ovary (pistil) on a stalk (pedicel).