Which of the following is a main element of an expert system?

The main element of an expert system is the user interface. An expert system is designed to solve complex problems by emulating the decision-making ability of a human expert. The user interface plays a crucial role in how users interact with the system. It enables users to input data, ask questions, and receive solutions or recommendations based on the knowledge the system has been programmed with.

An effective user interface is essential for ensuring that users can easily navigate the system, input information correctly, and interpret the outputs accurately. This accessibility is vital for the practical use of expert systems in various applications, such as medical diagnosis, financial forecasting, and troubleshooting technical issues.

While application libraries, network configurations, and hardware specifications can support the functioning of an expert system, they are not considered main elements in the same way that the user interface is, as they focus on the technical backend rather than the user interaction experience.