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: hydropower requires damming a river, Fact2: Another source of energy is hydropower., Question: What is a source of energy? (A) fossil fuels (B) cooking (C) damming a river (D) sleeping (E) napping (F) Electrical energy (G) our nearest star (H) sunlight
[A]: C


[Q]: Fact1: Antigens are molecules that the immune system recognizes as foreign to the body., Fact2: Antigens prompt the body to produce antibodies., Question: Antigens are molecules that prompt the what of antibodies? (A) termination (B) failure (C) humans (D) decrease (E) production (F) anemia (G) rapid expansion (H) kinetic
[A]: E


[Q]: Fact1: Echinoderms lack a centralized nervous system., Fact2: Sand dollars and sea biscuits are also echinoderms., Question: What lacks a centralized nervous system? (A) Damaged hearing (B) Humans (C) Horses (D) Sand dollars (E) insects (F) Chickens (G) Pesticides (H) barnacles
[A]:
D