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: Of these research projects, which is the best choice for a student who is interested in environmental issues to study?  
 (A) making cars run on less fuel (B) finding more sites for copper mines (C) making ocean liners bigger and faster (D) replacing human workers with robots

A: A
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Q: Sooj learned that whales use vocalization to navigate and to communicate with other whales. Some scientists think that noise pollution in whale habitats may harm whale populations. What would be the most likely effect of noise pollution on whales?  
 (A) alteration of whale genetic material (B) reversed flow of energy through whale habitats (C) reduced populations of food organisms in whale habitats (D) separation of whale family groups

A: D
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Q: Scientific models are very common. For which purpose below would a physical model be least helpful?  
 (A) simulating scientific phenomena (B) simplifying a complex idea (C) allowing visualization (D) displaying data

A:
D
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