You will be given a definition of a task first, then some input of the task.
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").

Fact1: Echinoderms have a unique water vascular system with tube feet., Fact2: Each starfish arm is lined with tube feet., Question: Where does a starfish have its water vascular system? (A) salt and water. (B) Chlorophyll (C) the environment (D) in its arms (E) on the rocks (F) in its eyes (G) Epidermis (H) in the ocean
Output:
D