Which documentation is required for an audit in accordance with generally accepted auditing standards?

a. A flowchart or an internal control questionnaire that evaluates the effectiveness of the entity’s controls.

b. A client engagement letter that provides details of timing of each significant audit procedure and personnel performing that procedure.

c. An indication in the working papers that the accounting records agree or reconcile with the financial statements.

d. The basis for the auditor’s conclusions when the assessed level of control risk is at the maximum level for all financial statement assertions.