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").

Fact1: Immunodeficiency occurs when the immune system is not working properly., Fact2: Iron deficiency causes anemia and it weakens the immune system., Question: What can low iron cause? (A) contamination (B) Pollution (C) decrease stamina (D) harmful substances (E) immunodeficiency (F) the ground shaking (G) cloudy and rainy weather (H) Temperature changing
E