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: All life relies on a relatively narrow range of pH, or acidity., Fact2: All organisms have life cycles., Question: what relies on a relatively narrow range of acidity? (A) organisms (B) carbon (C) animals (D) hydrogen (E) density (F) trees (G) Most plants (H) barnacles
[EX A]: A

[EX Q]: Fact1: Molecules of tRNA bring amino acids to the ribosome in the correct sequence., Fact2: Ribosomes are sites of protein synthesis., Question: Molecules of _ initiate protein synthesis (A) Acids (B) nektar (C) sugar (D) tRNA (E) H 2 O (F) three (G) CO 2 (H) HIV
[EX A]: D

[EX 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
[EX A]:
E