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