You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Q: A scientific guess about the cause and effect of an event is called  
 (A) a variable. (B) a theory. (C) a hypothesis. (D) an observation.

A: C
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Q: In 1971, the bones of an extinct flying dinosaur were discovered. This kind of discovery helps everyone learn more about  
 (A) impact of humans on Earth. (B) effect of gravity on animals. (C) history of animal species on Earth. (D) likelihood that dinosaurs will reappear.

A: C
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Q: Use the information below to answer the question. Cotton is a plant product used to make fabric. Cotton is made of cellulose, a fiber not digestible by humans. Cellulose is composed of many sugar molecules bonded together into long chains. Each sugar molecule contains carbon, hydrogen, and oxygen atoms. When cotton fabric is washed, wrinkles often form. The clothing industry uses chemicals to manufacture some cotton fabrics that are wrinkle-free. Dyes are also added to color the cellulose fibers in cotton. How would a clothing manufacturer separate colors to determine the purity of the dyes?  
 (A) through filtration (B) by their boiling points (C) by their freezing points (D) through paper chromatography

A:
D
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