Which of the following is an example of lifestyle symptoms related to potential fraud?

The choice highlighting the buyer living beyond their known salary represents a significant lifestyle symptom that could indicate potential fraud. This behavior suggests that the individual's expenses exceed their documented income, which may raise red flags regarding possible dishonest activities, such as embezzlement or financial misrepresentation. Individuals who engage in fraudulent activities often develop lifestyles that do not align with their legitimate income levels, leading to financial discrepancies and suspicion.

In contrast, the other options describe behaviors that, while they may be concerning in a professional context, do not directly correlate with potential fraudulent activity as effectively. Not relating well to other buyers may indicate interpersonal issues but does not provide clear evidence of financial misconduct. Frequently ordering from unapproved vendors might suggest non-compliance or poor vendor management but does not inherently imply that fraud is occurring. Increased work productivity could reflect positive engagement or improvements in performance and lacks a direct link to suspicious financial activity.