![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
Researchers have found that______.
A.
the quantity of cracks decides the speed of an earthquake
B.
the larger amount of pressure, the faster the transmission signals are
C.
the larger the magnitude is, the longer pre-seismic signals an earthquake have.
D.
the stress signal is detectable with two sensors a few yards away from each other