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.

the answer your looking for is c. : )

answer; ( correlation );