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").
Q: Fact1: water causes refraction of light, Fact2: Water is a compound of hydrogen and oxygen., Question: What causes a refraction of light? (A) compound of hydrogen oxygen (B) focusing a lens (C) that material's properties (D) photosynthetic pigments? (E) oxidation reaction (F) a hemisphere is tilted away from the sun (G) sunlight beams (H) solid, liquid, gas
A:
A