Students observed a plant left by a window over several days. The plant was watered daily. After three days, the plant began to grow towards the window. Why is the plant growing towards the window?

Heat from the Sun caused the plant to grow towards the window.
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The plant is leaning towards the window to get fresh air.
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The plant is responding to the stimulus of sunlight.
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The plant is responding to water in the air and growing towards it.