The adjustment of materials that follow a major earthquake often generates smaller earthquakes called?
foreshocks
surface waves
aftershocks
body waves

The right option is; Aftershocks

The adjustment of materials that follow a major earthquake often generates smaller earthquakes called aftershocks.

Aftershocks are lower intensity earthquakes that follow the main (largest) shock of an earthquake sequence. Aftershocks are usually smaller than the main shock, but they tend to be the most severe and occur more often in the hours and days after an earthquake. The larger the main shock, the larger the aftershocks. However, the intensity and magnitude of aftershocks reduces over time.  

the denominator has a very specific role.