The three primary occupant response strategies to a fire event are total evacuation, partial evacuation, and defend-in-place. Total evacuation involves all occupants leaving the structure. Partial (or phased) evacuation is the controlled evacuation of occupants in immediate danger first, typically on the fire floor and adjacent floors. Defend-in-place is a strategy where occupants remain within a protected area inside the building, relying on the structure's fire-resistive construction and compartmentation for safety. This is common in facilities like hospitals or high-rises where evacuation may be impractical or hazardous.

A. "Pull evacuation" is not a standard or recognized term for an occupant response strategy in fire protection engineering or NFPA standards.

C. Horizontal exits are a component of a means of egress system that allows movement to an area of refuge, not an overall response strategy.

D. Vertical exits, such as stairways, are a component of a means of egress system used to facilitate evacuation, not a response strategy itself.

1. SFPE Handbook of Fire Protection Engineering, 5th Edition. Chapter 53, "Movement of People: The Evacuation Process," Section 53.4.1, "Evacuation Strategies." This section explicitly outlines the three main strategies as "Total evacuation," "Phased evacuation" (a type of partial evacuation), and "Defend-in-place." (DOI: 10.1007/978-1-4939-2562-453)

2. NFPA Fire Protection Handbook, 21st Edition. Volume 1, Section 8, Chapter 1, "Concepts of Egress Design," pp. 8-10 to 8-11. The text discusses various egress strategies, including total building evacuation, zoned or phased evacuation, and defend-in-place, noting the latter is suitable for occupancies where occupants are incapable of self-preservation.

3. Oklahoma State University, Fire Protection & Safety Engineering Technology Program. Course materials for FST 3333, "Fire Protection Systems," cover life safety systems and egress. Lecture notes on Life Safety Concepts detail the primary evacuation and occupant protection strategies, identifying total evacuation, partial/phased evacuation, and defend-in-place/shelter-in-place as the core approaches.