This shouldn't be in Biology, by the way. I would say Science or Geography.
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So... let's see.
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First of all, the answer is C.
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Why?
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You see, let's do a virtual experiment you can imagine in your mind.
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Take a flashlight and crumple up several pieces of paper. Put a stick right through the middle of the crumpled ball.
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Go to a dark room, then turn on the flashlight and aim it at the ball. Tilt the top stick towards you, 30 degrees. Now do you see the light aiming at the bottom part of the ball? Now tilt the top stick towards the flashlight, the bottom stick tilted towards you, 30 degrees. Now the top part is being illuminated by the light!!
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This is Earth. When the Earth tilts one way, one hemisphere of the world receives heat or cold. When the Earth tilts the other way, everything is vice versa.
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So, it is C.
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Hope I helped!!
