Internal fire protection systems include hand-held fire extinguishers and:

• A. fire escapes
• B. water hydrants
• C. smoke control systems
• D. fire department connections

Answer: (C)

Internal fire protection systems are the facilities inside a building that help control a fire and protect occupants, including devices you can carry or activate and the built-in systems that manage heat and smoke. Hand-held fire extinguishers are a basic internal tool, and a smoke control system is the built-in system that actively manages smoke movement, pressure, and containment to keep escape routes tenable and to aid suppression efforts. Fire escapes are primarily means of egress, not fire protection systems. Water hydrants and fire department connections are connected to external water supplies and service outside the building’s internal protection setup. So, the best match for what pairs with hand-held extinguishers as an internal protection measure is smoke control systems.