Answer:
The correct answer is letter "C": Inference engines contain an explanation subcomponent.
Explanation:
An expert system is an attribute of Artificial Intelligence (AI) that allows solving problems where human intelligence could be limited. Expert systems are typically formed by a knowledge base and an inference engine. Inference engines are the data processing components of the expert systems. They are the tools that make deductions based on logical rules.
Inference engines do not provide an explanation. They provide deductions fed by the information provided by the knowledge base.