the answer is 21<span>% oxygen, </span>
Earth's crust are pushing against each other miles below the Earth's surface, causing earthquakes, volcanoes and the movement of the continents. Approximately 30 plates are mapped out throughout the world. The plates consist of the Earth's crust and of the mantle, which is a thick layer of hot rock. Below that lies a sea of magma.
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Defects in transcription factors underlie some forms of cancer.
