What do flight attendants use to communicate with each other during the flight regarding passenger needs?

The cabin communication system is the correct choice because it is specifically designed for in-flight communication among flight attendants. This system allows crew members to relay important information about passenger needs, emergencies, or other operational matters discreetly and efficiently. It typically includes intercoms, headsets, or other communication devices that ensure flight attendants can stay connected with one another throughout the flight without disrupting passengers.

Other options, while they serve communication purposes, are not typically utilized for inter-crew communication in the same way. Walkie-talkies may be effective in some environments but are not standard equipment on commercial flights for this purpose. The public address system is mainly used to communicate announcements to passengers rather than between crew members. The passenger service unit, which includes reading lights, air vents, and emergency oxygen masks, is primarily intended for passenger use and does not facilitate direct communication among the crew.