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: According to cell classification, prokaryotic cells are separated from eukaryotic cells. Which feature is often used to distinguish prokaryotic cells from eukaryotic cells?  
 (A) life processes (B) size differences (C) plasma membranes (D) energy molecules

A: B
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Q: Sandbars form in many rivers because of  
 (A) erosion of cliffs. (B) water flowing into a lake. (C) dams being built by beavers. (D) sediment being moved downstream by water.

A: D
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Q: Some new cars use special braking systems to recover energy when the brakes are applied. This energy is stored in special batteries and is used to power the electric motor. What type of energy are the brakes storing as they slow down the car?  
 (A) gravitational (B) kinetic (C) potential (D) thermal

A:
C
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