Combustion by moving pistons which respond to a change in pressure.
heat engines
refrigeration units
furnaces
heat pumps

The correct answer is heat engines.

Explanation:

Heat engine is a device that uses heat to perform some work. Heat engine consists of a gas present in the cylinder with piston.

If a gas is heated then the gas will expand. Then the piston moves up. If the gas is cooled down then the piston moves backward. There is a cycle of heating and cooling which leads to move the piston up and down due to change in pressure.

Therefore, heat engines use combustion by moving pistons which respond to a change in pressure.

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explanation:

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the entire statement is true and correct.  

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