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: Most invertebrates have a nervous system., Fact2: Narcotic analgesics act on the central nervous system to relieve pain., Question: How do most analgesics work on invertebrates? (A) insects (B) kinetic (C) adding heat (D) reduce (E) decrease stamina (F) it needs them (G) Relieve pain (H) protect them
G