Which of the following is not true about the production rules that are used in expert systems developed to assist auditors?

a. They are used to represent the heuristics sometimes employed by auditors to make judgments

b. They are the only technique currently available for storing the knowledge that characterizes the audit domain

c. The antecedent part of a production rule specifies the condition that leads to a particular action

d. They are stored in the knowledge base of an expert system