Given the task definition and input, reply with output. 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: Mollusks are a major food source for other organisms, including humans., Fact2: Mollusks are invertebrates and are no exception., Question: What is a major food source for humans? (A) poison dart frogs (B) honeybees (C) barnacles (D) intervertebrates (E) other humans (F) photosynthesis (G) the body's largest organ (H) Most plants
D