根据以下内容回答题：
Earthquakes may rightly be ranked as one of the most destructive forces known to man: since reeords began to be written down, it has been estimated that earthquake-related fatalities （死 亡）have numbered in the millions, and that earthquake-related destruction has been be-vond calculation. The greater part of such damage and loss of life has been due to falling down of buildinqs and the effects of rockslides, floods, fire, disease, gigantic sea waves, and other phenomena (现象)resulting from earthquakes, rather than from the quakes themselves . The great majority of all earthquakes occur Off two specific areas, along the coasts of the Pacific Ocean and from the East Indies to the Atlas Mountains. But they may, however, happen anywhere at any time. This element of the unknown has for centuries added greatly to the fear and horror sur-rounding earthquakes, but in recent times there have been indications that earthquake prediction may be possible. By analyzing changes in animal behavior, patterns of movements in the earth's surface and other unusual phenomena, scientists have shown increasing Success in predieting when and where earthquakes will strike. As a result, a worldwide earthquake-warning network is already in operation and has helped to prepare for the vast destruction that might otherwise have been totally unexpected. It is. doubtful, that man will ever be able to control earthquakes and do away with the destructiveness altogether.but as how. and why earthquakes happen become better understood, man will become more and more able to deal with their possible destruction before it occurs .
3. “This element of the unknownin ”the third paragraph refers to the fact that
Aearthquake—related destruction has been beyond calculation
Bmillions of people have died during earthquakes
Cearthquakes may occur anywhere at anytime
Dthere are other phenomena resulting from earthquakes
