Darrel was dancing with his new girlfriend at an Elvis tribute. When the band started playing, "Can’t Help Falling in Love with You," his girlfriend gave him a long, passionate kiss, which Darrel found very enjoyable. Now Darrel finds that every time he hears "Can’t Help Falling in Love with You" on the radio, he becomes mildly excited. In this example, the long, passionate kiss is

an unconditioned stimulus

Explanation:

Unconditioned stimulus: In psychology, the term "unconditioned stimulus" is described as one of the different aspects that is being included in the classical conditioning theory and was proposed by Ivan Pavlov. Unconditioned stimulus is also denoted as UCS or US and is considered as a stimulus that tends to elicit a response automatically, unconditionally, or naturally.

In the question above, the long, passionate kiss is an unconditioned stimulus.

is there a answer choice?