What does scalability refer to in a computer system?

Scalability in a computer system is fundamentally about its capability to handle growing amounts of work or its potential to accommodate growth without compromising performance. This means that a scalable system can adjust effectively, whether by increasing hardware resources (such as CPUs, memory, or storage) or by improving software efficiency to maintain or enhance performance as the workload increases. This characteristic is crucial for organizations that anticipate growth or fluctuating workloads, as it ensures that the system remains effective without requiring substantial redesign or replacement.

In contrast, the other options focus on aspects that do not accurately encapsulate the essence of scalability. For instance, decreasing performance or limiting capabilities goes against the definition of scalability, which inherently involves accommodating increased demands rather than reducing responsiveness or efficiency. Furthermore, while a system can indeed be designed to scale down, scalability is typically discussed in terms of growth and adaptation to increasing demands. Lastly, describing a system as rigid contradicts the flexible nature that is intrinsic to scalability, as a scalable system should be able to evolve and adapt.