Just before something scary happens in a horror film, they often play scary sounding music. when i hear the music, i tense up in anticipation of the scary event. in this situation, the music serves as a

It serves as a "Conditioned stimulus".

In the classical conditioning there are conditioned stimulus as well as unconditioned stimulus. A conditioned stimulus is something which otherwise used to be a neutral stimulus but then it was connected to an unconditioned stimulus resulting in producing a conditioned response. In the given case the sound of music was previously neutral but being connected with the scary scene it triggers the frightening response which is conditioned response.

answer; face validity;