Question

what was one of the key features of marie van brittan browns home security system? a video camera on a sliding mechanism that allowed users to monitor and record their front door an alert signal that would summon the police or members of the neighborhood watch a motion - activated floodlight and alarm system that would deter anyone attempting to break in

Explanation:

Marie Van Brittan Brown's home security system had a key feature of an alert signal that summoned police or neighborhood watch. The other options: the video camera sliding mechanism isn't her system's key (her system used peepholes and a radio - like system to alert), and the motion - activated floodlight/alarm wasn't the main key feature as her system focused on alerting authorities/neighbors.

Answer:

B. an alert signal that would summon the police or members of the neighborhood watch (assuming the middle option is B, as per typical multiple - choice formatting with three options where the middle is about summoning help, which is a core feature of her system)