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").
Q: Fact1: Fertilization occurs when a sperm and an egg fuse., Fact2: Sperm and eggs are cells known as gametes., Question: What causes fertilization? (A) pollen (B) infertility (C) gametes (D) orchids (E) seeds (F) no physical contact (G) honeybees (H) isolation
A:
C