Which of the following factors is the MOST important to consider when choosing an uninterruptible power supply (UPS) for a single server?

UPS form factor is important for physical installation and space, but it does not directly impact the UPS's primary function of providing backup power and preventing data loss.

Server form factor is irrelevant to UPS selection; UPS selection is based on power requirements, not the physical dimensions of the server it protects.

While the server's wattage rating is necessary to ensure the UPS has sufficient capacity (VA/watts), it is a prerequisite for selecting a suitable UPS model, not the ultimate determining factor for its effectiveness in an outage compared to runtime.

Desired runtime is the MOST important factor because it dictates how long the UPS can supply power to the server during an outage. This duration is critical to allow for a graceful shutdown of the server to prevent data loss or corruption, or to bridge short power interruptions until utility power is restored.