Answer :
Answer;
D. It's a numerical system that measures the smallest seismic waves during an earthquake.
Explanation;
-The Richter magnitude scale is a scale of numbers used to tell the size of earthquakes. It is a standard scale used to compare earthquakes. The scale was invented by Charles Francis Richter and was based on the seismogram measured by a particular type of seismometer at a distance of 100 kilometres (62 mi) from the earthquake.