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How is a rockfall different from a rockslide?
A. In a rockfall, a mass of rocks slides together, whereas in a rockslide, blocks of rock drop freely.
B. In a rockfall, individual blocks of rock drop freely, whereas in a rockslide, a mass of rocks slides together.
C. In a rockfall, a mountain slope collapses after heavy rains, whereas in a rockslide, large masses of rock fall after an earthquake.
D. In a rockfall, an earthquake triggers rocks to slide together, whereas in a rockslide, a mountain slope collapses after heavy rains.
What is D. In a rockfall, an earthquake triggers rocks to slide together, whereas in a rockslide, a mountain slope collapses after heavy rains?