Under the circumstances described, the type of fraud most likely to occur is skimming. Skimming involves stealing cash before it is recorded on the organization's books. Since receipts were issued only upon request and the inventory manager had control over collecting and depositing payments, there is an opportunity for undetected theft of cash payments.
Common types of fraud in cash handling environments, as outlined in fraud detection and prevention resources by the IIA.

Due professional care involves the exercise of professional judgment and the application of care that an ordinarily prudent person would use under the circumstances. In scenario A, the chief audit executive demonstrates due professional care by excluding an auditor who previously worked in the payroll department from the audit team assigned to audit that area. This action avoids conflicts of interest and ensures the objectivity of the audit, aligning with IIA guidelines on independence and objectivity in internal auditing.
IIA Standard 1100: " Independence and Objectivity "

Posting the organization's code of conduct on its website is a strategy to mitigate cultural risk by promoting transparency and establishing a clear set of behavioral expectations for both employees and stakeholders. This helps in shaping a positive organizational culture where ethical behavior is encouraged and deviations from expected conduct are minimized. By making the code of conduct publicly available, the organization demonstrates its commitment to integrity and ethical behavior, which can enhance trust and accountability.
References: The IIA's International Standards for the Professional Practice of Internal Auditing (Standards), specifically Standard 2110 - Governance, and COSO's Internal Control - Integrated Framework.

Completing a skills assessment and development plan specifically targets the auditor ' s training needs, thereby demonstrating a direct commitment to developing professional competencies. This approach is strategic as it identifies gaps in skills and knowledge, and provides a structured path towards professional development tailored to the auditor's current and future roles.
IIA guidelines on Continuing Professional Development

Ethics are indeed not defined by laws alone; they are based on standards of conduct derived from shared principles and values. This statement most accurately reflects the nature of ethics in the context of corporate social responsibility (CSR), emphasizing that while ethics are guided by laws, they fundamentally originate from broader societal values and the ethical norms of the community.
Basic ethical principles in CSR and business ethics literature