The speed of seismic waves varies as they travel through Earth because
A. Temperature varies within the Earth
B. Density of rocks varies within the Earth
C. The composition of rocks varies within the Earth
D. All of the above
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When new rock is added to an oceanic ridge, the magnetized strips on either side of the ridge are evidence of sea-floor spreading. this is because the rocks on the two sides of the ridge o are equal in width and in polarity are polar opposites oare magnetized vary in width but are equal in polarity