Answer:
Lisa is suffering from background noise.
Step-by-step explanation:
Lisa stops listening to the lecture and begins worrying about what questions may appear on the exam. Lisa is suffering from background noise. Lisa has stopped listening to the lecture and wants to focus on the exam. She is not able to do it because the noise that is present in the room prevents her from focusing. Background noise is the noise that is present in the classroom while she is trying to think about something crucial for her.