Final answer:
In the described scenario, the Conditioned Response is the action of students closing their books and beginning to pack up their backpacks, following the teacher's use of the word 'tomorrow'.
Step-by-step explanation:
The Conditioned Response (CR) in this scenario is a) Closing books and packing up. This response has been learned by the students when they hear Ms. Fenton say the word "tomorrow," which has become a conditioned stimulus associated with the end of the class period. The excitement felt by the students is an internal emotional response, while the action of closing books and beginning to pack their backpacks is the external behavioral response, which is the conditioned response in classical conditioning.