Of the Following,which Is the BEST Description of Pavlov's Accidental

Of the following,which is the BEST description of Pavlov's accidental discovery?

A) The dogs learned a reflexive response (salivating) to a stimulus (food) .
B) The dogs learned a reflexive response (salivating) to a neutral stimulus (laboratory attendant) .
C) A neutral stimulus (laboratory attendant) rewarded the dogs by giving them a reflexive stimulus (food) .
D) A reflexive response (salivating) became associated with a neutral stimulus (laboratory attendant) .