Definition: 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: Endocrine hormones travel throughout the body in the blood., Fact2: Deficiencies in the Endocrine System are another source of impotence., Question: Lack of what in the blood can lead to impotence? (A) hormones (B) hemoglobin (C) oxygen (D) iron (E) Energy. (F) t-cells (G) competition (H) Energy
Output:
A