The ability of a system to handle the increase in demand without impacting the application's performance or availability is known as:

• A. Threshold
• B. Usability
• C. Scalability (KPI)
• D. Public Data

Answer: (C)

Scalability—the system’s ability to grow or adapt to increasing demand without sacrificing performance or availability. When workload rises, a scalable design can absorb it by adding resources or optimizing behavior so response times stay fast and services remain online. In practice this means supporting strategies like horizontal or vertical scaling, load balancing, auto-scaling, and caching, so throughput can increase while latency and error rates stay within acceptable limits. This concept is often tracked with KPIs such as throughput, latency, and error rate under higher load. Thresholds describe fixed limits that trigger actions, usability is about how easy the system is to use, and public data is unrelated to performance characteristics. So scalability is the best fit.