Final answer:
Internal auditors are likely to focus on the timing of revenue recognition and the valuation of inventories, as well as whether accounting estimates are reasonable given past actual results. Option C is correct.
Step-by-step explanation:
Based on the information provided, the internal auditors are likely to focus on C. The timing of revenue recognition and the valuation of inventories. This is because the manipulation of earnings on quarterly financial statements suggests a need to examine the accuracy and completeness of revenue recognition and inventory valuation methods. By examining these areas, the internal auditors can assess whether there are any discrepancies that could lead to artificially inflated net profit figures.
In addition, the internal auditors may also look into D. Whether accounting estimates are reasonable given past actual results. This is important to ensure that the accounting estimates used in the interim financial statements are consistent with past performance and reflect the true financial position of the organization.
While A. Whether payables have been accrued properly at the end of the interim period and B. Whether there have been changes in accounting principles that materially affect the financial statements may also be areas of focus for internal auditors, they may be of lesser importance in this specific situation compared to revenue recognition, inventory valuation, and accounting estimates.