Which of the Following Pieces of Evidence Recently Led Scientists

Which of the following pieces of evidence recently led scientists to propose that great earthquakes occur in Oregon,Washington,and British Columbia every 500 to 600 years?

A) dramatic increases in the number of small (M = 6) earthquakes
B) geologic records of flooded,dead coastal forests
C) groundwater records showing dramatic fluctuations in the water table
D) seismograph records of great earthquakes that were previously underestimated