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: Five bowling balls are lined up touching one another on a smooth surface. Striking the first ball with a hammer makes the fifth ball move away from the group. The force of the hammer was transmitted through the line of balls as what type of wave?  
 (A) electromagnetic (B) heat (C) longitudinal (D) transverse

A: C
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Q: Farmers plant fruit trees in an area that was once a grassy meadow. Which will most likely happen to the rabbits living in the meadow?  
 (A) They will learn to eat fruit. (B) They will learn to climb trees. (C) The number of their young will increase. (D) The size of their population will decrease.

A: D
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Q: In 2014, a break in a storm water pipe released thousands of gallons of coal ash from a retired electrical plant into a river. The spill occurred upstream from the water treatment plants that serve communities along the river. Coal ash contains several hazardous metals including arsenic. Which stage of the water treatment process is most likely to remove hazardous metals from the water?  
 (A) aeration (B) coagulation (C) disinfection (D) reverse osmosis

A:
B
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