The correct answer is A. High temperatures activated the fire suppression system. According to CompTIA DataSys+ objectives, physical infrastructure protections are a critical component of database and data center reliability. CO₂ fire suppression systems are specifically designed to respond to fire-related conditions, not recovery metrics or cooling system logic. These systems are typically triggered by smoke detectors, heat sensors, or rapid temperature increases that indicate a fire or imminent fire risk following an event such as a power failure.

When a power outage occurs, backup systems such as generators and uninterruptible power supplies may activate. If these systems malfunction or generate excessive heat, temperature thresholds can be exceeded within minutes. DataSys+ materials emphasize that automated environmental controls are designed to protect equipment and data by suppressing fires quickly, often before flames are visible. CO₂ systems work by displacing oxygen, thereby extinguishing fire without damaging sensitive electronic equipment with water or chemical residue.

Options B and D are incorrect because RPO (Recovery Point Objective) and RTO (Recovery Time Objective) are disaster recovery planning metrics. RPO defines acceptable data loss measured in time, while RTO defines acceptable downtime. Neither setting directly triggers physical fire suppression systems. They are planning and policy metrics, not automated environmental controls.

Option C is also incorrect because cooling systems do not activate CO₂ fire suppression. Cooling failures may indirectly contribute to rising temperatures, but the CO₂ system itself is triggered by fire detection mechanisms, not by cooling system logic.

CompTIA DataSys+ clearly distinguishes between environmental controls (fire suppression, HVAC, power) and disaster recovery metrics (RPO, RTO). Therefore, option A best aligns with documented data center operational behavior and exam objectives.