You are given a science question (hard-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: The students in a class are making a scale model. They need a material that they can easily bend into a circle. Which of the following objects is best for the students to use?  
 (A) copper wire (B) glass rod (C) lead pipe (D) wooden stick

A: A
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Q: Scientists discovered that although infectious bacteria may develop immunity to antibiotic medications, some bacteria are unable to resist certain peptides, which act as natural antibiotic substances inside the human body. This discovery led to the development of which new technology?  
 (A) artificial substances that mimic human peptides (B) antibiotics that can be absorbed through the skin (C) bacteria that attack antibiotic-resistant organisms (D) antibiotics that adapt in response to bacterial immunity

A: A
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Q: Most farmers use fertilizers on their cornfields. Which statement best explains why farmers should not use excess amounts of fertilizers?  
 (A) Fertilizers may wash into streams. (B) Fertilizers may be used by weeds. (C) Fertilizers may evaporate into the air. (D) Fertilizers may come from natural materials.

A:
A
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