*Q:17 Correct Answer* ✅ *(4) A is false but R is true* > *Explanation:* The water vascular system is a characteristic feature of echinoderms (e.g., starfish), not sponges. However, sponges have ostia (pores) through which water enters into the spongocoel, and water exits through the osculum. This system is called the canal system, not the water vascular system.