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: knowledge of the stars can be used to navigate, Fact2: Of course, astronomers also study stars., Question: What can be used to navigate? (A) music (B) backbones (C) astrology (D) cilia (E) magic (F) sponges (G) astronomy (H) lamphreys
[EX A]: G

[EX Q]: Fact1: a graduated cylinder is used to measure volume of a liquid, Fact2: Volume is typically measured in liters or milliliters., Question: What could be used to to measure how many milliliters something is? (A) solid, liquid, gas (B) A graduated cylinder (C) objects that have mass (D) an electron microscope (E) The bending of a ray of light (F) deoxyribonucleic acid (G) a hydraulic system (H) microscope
[EX A]: B

[EX Q]: Fact1: chemical weathering causes iron in rock to oxidize, Fact2: Oxides Oxides Oxides are elements combined with oxygen., Question: Chemical weathering causes iron in rock to combine with what? (A) uranium (B) oxygen (C) cartilage (D) nothing (E) an object (F) vacuum (G) energy (H) heat
[EX A]:
B