Final answer:
Non-diegetic sound is the sound whose source comes from the imaginary world of the fiction represented. The correct option is b.
Step-by-step explanation:
The sound whose source comes from the imaginary world of the fiction represented is non-diegetic sound. Non-diegetic sound refers to sound that does not originate from the fictional world, but is added to enhance the audience's experience. It includes background music, voiceovers, and sound effects that are not heard by the characters in the story.
For example, in a movie, if there is dramatic music playing during a suspenseful scene, that music is non-diegetic sound because the characters in the movie cannot hear it. However, it adds tension and emotion for the audience.
Hence, Option b is correct.