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").
Problem:Fact1: Adult sponges are sessile., Fact2: Hydras are sessile, attaching to some sort of substrate., Question: Where do adult sponges attach themselves? (A) animal (B) stalk (C) Sediment (D) coastlines (E) plant (F) substrate (G) ocean water (H) loose soil
Solution:
F