Which of the Following Best Describes a Seismic Gap

Which of the following best describes a seismic gap?

A) A section of an active fault that has not experienced an earthquake for an extended period of time
B) A large crack in the ground that opens in response to earthquake activity.
C) The time interval between when an earthquake originates and when it's felt at distant locations.
D) The time interval between when an earthquake originates and when its aftershocks begin.
E) A portion of a seismograph record where data is missing due to seismic waves being blocked by a mountain range.