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: Veins generally carry deoxygenated blood., Fact2: Blood returns to the heart by the veins., Question: what supplies the heart? (A) organ (B) Energy (C) veins (D) ovaries (E) glucose (F) oxygen (G) sugar (H) alveoli
A:
C