Detailed Instructions: In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").
Q: Fact1: Echinoderms have a unique water vascular system with tube feet., Fact2: Another group of echinoderms are the echinoids., Question: Which has a unique water vascular system? (A) roots (B) trees (C) Conifers (D) Echinoids (E) fur seals (F) Most plants (G) ferns (H) bushes
A:
D