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: Which series correctly represents the levels of organization in an organism?  
 (A) cells -> organs -> organ system -> tissue (B) cells -> tissue -> organs -> organ system (C) tissue -> cells -> organ system -> organs (D) tissue -> organ system -> cells -> organs

A: B
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Q: What happens when water flows over a rock for a long period of time?  
 (A) erosion (B) flooding (C) breakage (D) evaporation

A: A
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Q: Ann makes hats for people. She has each person select the fabric and a hat style before she makes the hat to fit the person's head size. Which type of manufacturing system is Ann most likely using to make hats?  
 (A) mass production (B) custom production (C) automated production (D) assembly line production

A:
B
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