In 1870, the Chicago Police Department updated their signal lights with:

• A. Clock boxes
• B. Call booths
• C. Call boxes
• D. Private booths

Answer: (C)

The main idea is how police communication evolved to get help quickly from the field. In 19th-century Chicago, signaling devices on the streets were used to summon the central station and direct patrol units. Call boxes were the installed devices that enabled a signal from the scene to reach the dispatcher, allowing rapid deployment of officers to a reported incident. This method fits the purpose of updating signal lights to a dispatch-capable system.

Clock boxes would serve timekeeping signals, not dispatch. Call booths would imply a communication setup like a phone booth, which wasn’t standard for police signaling at that time. Private booths aren’t part of the public dispatch network. So, call boxes best match the function of updating signal lights to facilitate fast, centralized communication.