What is a primary characteristic of the SI system?

The primary characteristic of the SI (International System of Units) system is that it is based on the metric system. This system provides a standardized framework for measuring various physical quantities, such as length, mass, time, and temperature, using units like meters, kilograms, seconds, and kelvins. The clarity and consistency of the metric system help ensure that measurements can be universally understood and applied in scientific research, education, and practical applications.

In contrast, the other options present ideas that do not accurately describe the SI system. The SI system is intentionally designed to have consistent measurements across different fields and applications. It is widely adopted not only in scientific contexts but also in everyday life, making it accessible and practical for various uses. Furthermore, the SI units are recognized and used internationally, indicating a broad acceptance rather than a limited or region-specific application.