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: The parts of plants that make seeds are the  
 (A) roots. (B) stems. (C) flowers. (D) leaves.

A: C
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Q: Which is an example of a chemical reaction?  
 (A) Vinegar added to baking soda forms a gas. (B) Water evaporates into air. (C) Sugar dissolves in water. (D) Corn kernels are crushed to form flour.

A: A
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Q: Nitrogen, a nutrient found in fertilizer, helps plants increase in size. Rainwater runoff often carries fertilizer into ponds and lakes. What effect does excess nitrogen have on organisms in a pond or lake ecosystem?  
 (A) Algae grows rapidly. (B) Mutations occur gradually in fish. (C) Clam shells are slowly weakened. (D) Frogs adapt quickly to new food sources.

A:
A
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