Answer: The physics principle that explains the basics of how a seismograph's recorder works is:
(A) Inertia
A seismograph is an instrument used to detect and record seismic waves, which are generated by earthquakes and other geological events. It relies on the principle of inertia, specifically the fact that an object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an external force. The seismograph's mass is suspended in a fixed frame, and when the ground shakes due to seismic activity, the frame moves while the mass inside tends to stay in place, causing the mass to move relative to the frame. This relative motion is then recorded on a rotating drum or digital sensor, allowing scientists to analyze the seismic waves and gather information about the earthquake's characteristics.