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").
Input: Fact1: when light enters the eye through the pupil , that light falls on the retina, Fact2: Humans use both eyes to see a single image., Question: What do humans use to see an image? (A) keratin (B) light (C) heat (D) fibers (E) calcite (F) mussels (G) photons (H) Neuron.
Output:
B