Which of the Following Studies Has Employed Backward Conditioning

Which of the following studies has employed backward conditioning?

A) Presenting a flashing light after an electric shock is administered to a rat's tail
B) Presenting a flashing light a long time before an electric shock is administered to a rat's tail
C) Presenting a loud noise before a puff of air is blown on a cat's face
D) Presenting a flashing light at the same time when a puff of air is blown on a cat's face