Due professional care refers to the level of diligence, competence, and thoroughness expected of an auditor in the performance of their duties. An auditor demonstrating a good understanding of the steps involved in carrying out a consulting engagement directly reflects the application of due professional care. This shows the auditor is competently performing their duties with the necessary knowledge and skills. The other options are related to organizational procedures or access issues rather than the auditor's personal competence and diligence.