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: Cell division is necessary for an organism to  
 (A) obtain nutrients. (B) grow and reproduce. (C) make proteins. (D) conserve matter and energy.

A: B
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Q: A student tosses a ball into the air. Which force causes the ball to fall back to the ground?  
 (A) gravity (B) magnetism (C) mechanical (D) friction

A: A
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Q: The empty spaces in a material are called pores. Porosity is the amount of empty space within a material. Permeability describes how well the pores in a material are connected. Which of these materials would make the most effective aquifer?  
 (A) a material that has high porosity and high permeability (B) a material that has high porosity and low permeability (C) a material that has low porosity and high permeability (D) a material that has low porosity and low permeability

A:
A
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