Organisms with true radial symmetry A. tend to be highly mobile. B. do not have a distinct head region and tend to be sedentary or passive drifters. C. can be divided into two matching halves along only one plane. D. have their sense organs, mouth, and brain clustered in the head.

Option-A

Explanation:

Radial symmetry refers to the symmetry in which the organism can be cut into the same half through any plane which can be observed in the organisms belonging to Cnidarians.

The organism with radial symmetry do not show a distinct head region and are considered to be passive drifters like observed in the corals, sea anemones, starfish.

Thus, Option-A is correct.