Use reasoning to lead to the answer of the following question:
The rotor was very loud and moved a lot of air, but it was how the what was able to lift straight up?\nOptions:\n- electric motor\n- jet engine\n- rotator\n- train\n- helicopter
 Reasoning process:
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Rotor is a component of a helicopter. Rotor helps the helicopter to lift straight up. Rotor creates noise and moves a lot of air. Therefore, the final answer is helicopter.
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