Final answer:
The communication breakdown happened at the receiver element when the pharmacy assistant daydreamed during the manager's explanation.
Step-by-step explanation:
In the scenario described, the communication breakdown occurred at the listener or receiver element of the communication process. This happened when the pharmacy assistant was daydreaming about the prom instead of paying attention to the pharmacy manager explaining service expectations. As a crucial part of the communication process involves the receiver being attentive to the speaker's message, daydreaming hinders the effective reception of that message, leading to a failure in communication.