A science class is investigating how the amount of sunlight affects the height of tomato plants. One group of plants is placed in a window that receives direct sunlight for eight hours a day. A second group is placed in a location that receives four hours of direct sunlight. A third group is placed in a closet with no sunlight. All plants receive the same amount of water and are planted in the same type of soil. In this experiment, which factor is the independent variable?
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A
The type of soil used for the plants.
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B
The final height of the tomato plants.
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C
The amount of sunlight the plants receive.
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D
The amount of water given to each plant.