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").

[EX Q]: Fact1: Antigens are molecules that the immune system recognizes as foreign to the body., Fact2: Children are born with an immature immune, or defense, system., Question: What are molecules that the defense system recognizes as foreign to the body? (A) Allergies (B) lungs (C) antigens (D) bacteria (E) parasites (F) atoms (G) red blood cells (H) acetic acid
[EX A]: C

[EX Q]: Fact1: darkness has a negative impact on photosynthesis, Fact2: Light is necessary for photosynthesis, a process that produces oxygen., Question: Darkness has a negative impact on which process of a plant? (A) slow and inefficient (B) chemical changes (C) circulatory systems (D) most organisms (E) fossil fuels (F) Abnormal cell growth (G) deoxyribonucleic acid (H) Oxygen production
[EX A]: H

[EX Q]: Fact1: Mutualism is a symbiotic relationship in which both species benefit., Fact2: Symbiotic relationships are common and add to the complexity of species interactions., Question: What is something that adds complexity to species interactions? (A) sea anemones (B) vibration (C) animals (D) pigmentation (E) anemones (F) several genes (G) mutualism (H) sponges
[EX A]:
G