题目内容：
根据以下内容，回答题。Passage Two
On the morning of November 18,1755, an earthquake shook Boston, Massachusetts.John Winthrop, a professor at Harvard College, felt the quake and awoke. "I rose," Winthrop wrote, "and lighting a candle, looked on my watch, and found it was 15 minutes after four. " John Winthrop went downstairs to the grandfather clock. It had stopped four minutes before, at 4 : 11. Except for stopping the clock, the quake had only thrown a key from the mantel ( 壁炉) to the floor.
The clock had stopped because Winthrop had put some long glass tubes he was using for an experiment into the case for care. The quake had knocked the tubes over and blocked the pendulum (钟摆). Winthrop, therefore, had the exact time that the earthquake had hit Boston. He looked at the key on the floor. The quake had thrown it forward in the direction of the quake's motion (运动) by a shock coming from the northwest, perhaps in Canada.
The text proves that__________. A．the power of nature is terrible
B．earthquakes happen most often during nighttime hours
C．the direction of an earthquake can be discovered
D．universities study the cause of earthquakes
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