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 lack a centralized nervous system., Fact2: From animal experiments, it seems to be a central nervous system toxin., Question: Echinoderms are resistant to some: (A) starfish (B) enzymes (C) Toxicity (D) pesticide (E) parasites (F) toxins (G) boats (H) chemicals
F