According to the Association of Certified Fraud Examiners (ACFE), expense reimbursement fraud is most frequently committed by individuals at the employee and manager levels. The ACFE's 2022 "Report to the Nations" indicates that employees perpetrated 40% of these schemes, while managers were responsible for 36%. Combined, these two groups account for 76% of all expense reimbursement fraud cases, which aligns with the "almost three quarters" figure stated in the question. Therefore, "Employee level" is the most appropriate answer, representing the broad category of non-executive/owner staff who are the most common perpetrators of this scheme.

A. Executive level: This is incorrect. While frauds committed by executives tend to cause higher median losses, they account for a much smaller number of expense reimbursement cases (approximately 23% when combined with owners).

C. Owner level: This is incorrect. Owners are a subset of the owner/executive category and are responsible for an even smaller fraction of cases compared to employees and managers.

D. Stakeholder level: This is incorrect. "Stakeholder" is a broad term that is not a specific perpetrator category used in ACFE research for internal fraud schemes like expense reimbursement.

1. Association of Certified Fraud Examiners (ACFE). (2022). Occupational Fraud 2022: A Report to the Nations. ACFE. Retrieved from https://legacy.acfe.com/report-to-the-nations/2022/.

Reference Point: Page 58, Figure 48, "How Position Affected Asset Misappropriation Schemes." The chart shows that for Expense Reimbursement schemes, 40% of cases were perpetrated by employees, 36% by managers, and 23% by owners/executives. The sum of employee and manager cases is 76%.

2. Association of Certified Fraud Examiners (ACFE). (2023). Fraud Examiners Manual, International Edition.

Reference Point: Section 2.1101, "Position." This section discusses perpetrator characteristics and references the statistical findings from the Report to the Nations, confirming that employees and managers commit fraud more frequently than owners/executives, although the latter group causes higher median losses.