The answer is C “volcanic activity was more common in the past than it is today
Grids and variables are used to find coordinates. Latitude and longitude coordinates
The correct answer is - Focus.
Focus of the earthquake, also referred to as hypocenter, is the location/point where the earthquake starts. It is usually few kilometres below the surface. At this spot the ground raptures after which seismic waves start radiating outward in all directions. The focus is located below the epicenter, or rather the epicenter is above it because the location of the epicenter is determined by the location of the focus, so the epicenter represents the closest point on the surface of the Earth from where the focus is.