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: a breathing mask is used for keeping harmful particles from entering the respiratory system, Fact2: Oxygen enters the respiratory system through the mouth and the nose., Question: Breathing masks are used to keep harmful particles from entering the mouth and the what? (A) body (B) eyes (C) air (D) skin (E) gullet (F) nose (G) ears (H) lungs
[A]: F

[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
[A]: G

[Q]: Fact1: beads of water are formed by water vapor condensing, Fact2: An example of water vapor is steam., Question: What forms beads of water? (A) Necklaces. (B) Steam. (C) Glass beads . (D) a wave (E) tiny (F) a solute (G) rain (H) Bracelets.
[A]:
B