Which of the following is an interior control used to counter access inside a building?

• A. Front doors as primary entry.
• B. Dropped ceilings with motion sensors inside to counter access through.
• C. Exterior cameras along the building.
• D. Fences around the perimeter.

Answer: (B)

Interior controls inside a building are measures that detect and deter movement once someone is inside. Dropped ceilings with motion sensors placed in the interior ceiling void provide an extra layer of surveillance inside the structure. If an intruder moves through the ceiling space or travels to restricted areas, the sensors trigger an alert, allowing security to respond quickly. This kind of countermeasure operates from within the building, unlike options that monitor or control entry from the outside, such as front doors at an exterior entry, exterior cameras along the outside of the building, or fences around the perimeter. So the interior, ceiling-based motion sensors best fit the idea of an interior control used to counter access inside a building.