11. The actual operation of an internal control system may be most objectively evaluated by a. Substantive tests of account balances based on the auditor's assessment of internal control strength. b. Selection of items processed by the system and determination of the presence or absence of errors and compliance deviations. c. Review of the previous year's audit working papers to update the report of internal control evaluation. d. Completing a questionnaire and owchart related to the accounting system in the year under audit