An off-the-shelf software package that implements an inference engine, a mechanism for entering
knowledge, a user interface, and a system to provide explanations of the reasoning used to generate
a solution is called:

A.
A knowledge base

B.
A knowledge acquisition system

C.
An expert system shell

D.
A neural network

Explanation:
An expert system shell provides the fundamental building blocks of an expert system and supports
the entering of domain knowledge. Thus, for an application that is not complex and does not require
the custom development of the components of an expert system, an expert system shell is a useful
tool that will save development time. *A knowledge base is a component of an expert system. *. A
neural network is another type of artificial intelligence system that uses the neurons of the brain as a
model and solves problems using nonlinear pattern-matching techniques and learning approaches.
*A knowledge acquisition system refers to the means of identifying and acquiring the knowledge to
be entered into the knowledge base. In simple terms, it is trying to determine how an expert thinks
when developing a solution to a problem.