Where did the horse originate

A．Altogether 1,480,000 people were killed in the earthquakes.
B．In the past, earthquakes happened twice in China.
C．China is within the "ring of fire".
D．In the history, China had two worst earthquakes that took an enormous number of human lives.

A．it occurs in the center of the earth, so experts cannot tell when earthquakes will occur
B．there is rushing water in the center of the earth
C．solid rocks under the ground move and strain against each other, causing the earth's surface moving
D．there are other unknown causes