Developing an audit finding involves comparing the condition to the relevant standard or criterion. which of the following choices best represents an appropriate standard or criterion to support a finding?
a: a quality standard operating procedure (number and date) for the department.
b: an internal accounting control principle, cited and copied from a public accounting reference.
c: a sound business practice, based on the internal auditor's knowledge and experience obtained during many audit assignments within the company.
d: all of the above