Which Geographic Phenomenon Is Most Responsible for the Constant Threat

Which geographic phenomenon is most responsible for the constant threat of earthquakes along the Pacific coast?

A) Magma underneath Earth's surface is pressing up on the crust with increasing pressure.
B) The Pacific Plate and the North American Plate are presently rubbing up against each other.
C) Pressure from increased ocean mass caused by global warming is creating structural instability underneath the continent.
D) Great quantities of industrial chemicals have leached into earth's crust, causing a breakdown in its composition.