What is scalability?

• A. The ability of a system to handle increasing load by adding resources.
• B. The security of a system under attack.
• C. The ability to run on multiple operating systems.
• D. The speed of processing increases with more hardware but doesn't depend on load.

Answer: (A)

Scalability is the ability of a system to handle increasing load by adding resources. As demand grows—more users, more transactions, more data—the system should keep performing well by expanding capacity. This can be done through vertical scaling (adding power to a single machine) or horizontal scaling (adding more machines and distributing the workload), often with tools like load balancers and data partitioning.

So the best answer captures the idea that performance remains solid as demand rises by increasing resources. The other options describe security, portability, or a hardware-only speedup that doesn’t depend on changing load, which aren’t about scaling to meet growing demand.