Simon witnessed the crash of a private plane at his local airport. He was also part of the initial rescue attempt to assist the pilot and passengers. Bill was saddened by the fact that all people on the plane perished. Every time Bill sees a small private plane in the air he remembers that fateful day when he saw a disaster first-hand. What type of memory is Bill using when he experiences these periodic flashbacks?

A. sensory memory

B. episodic memory

C. primary memory

D. elaborative memory.