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: When gasoline in a car engine is burned, only about 15 percent of the gasoline is converted into mechanical energy. This is because most of the energy in the gasoline is  
 (A) transformed into heat. (B) stored for use at a later time. (C) changed into chemical energy. (D) used to make the vehicle move.

A: A
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Q: A pot is touching the flame of a gas stove, and the substance in the pot is heating up due to the contact. This is an example of which type of energy transfer?  
 (A) radiation (B) convection (C) conduction (D) vaporization

A: C
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Q: Two pieces of the same metal are placed on a table. The pieces of metal have the same density, mass, and texture. Which characteristic must be the ONLY difference between the two samples?  
 (A) They have different dimensions. (B) They have different boiling points. (C) They are made up of a different type of matter. (D) They contain a different amount of matter per unit volume.

A:
A
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