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: Male dogs use pheromones in urine to mark their territory., Fact2: Pheromones are natural aphrodisiacs., Question: What do male dogs use in urine to mark their territory? (A) Natural aphrodisiacs (B) competing for resources (C) Tails (D) Urine cleaner (E) Something coming from a gland (F) Chemical energy (G) an area swollen with pus (H) Chew toys
A