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 of the following best describes an advantage of using a mass production manufacturing system instead of a custom manufacturing system?  
 (A) Customers can provide specific feedback to workers. (B) Workers become skilled in all aspects of assembly. (C) Goods can be easily modified for customers. (D) Products can be made at a lower cost.

A: D
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Q: Which is a major difference between the life cycles of different types of plants?  
 (A) the way they die (B) the energy they use (C) the way they reproduce (D) the way they make food

A: C
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Q: Frog eggs hatch into tadpoles, and then tadpoles gradually develop into frogs. This process is known as  
 (A) adolescence. (B) crossbreeding. (C) regeneration. (D) metamorphosis.

A:
D
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