What might indicate a money laundering scheme involving a single individual?

Transferring large sums of money to different accounts without clear justification is a strong indicator of a money laundering scheme involving a single individual. This behavior typically suggests an attempt to obscure the origins of funds and make them appear legitimate. The lack of transparency with these transactions can raise red flags for financial institutions and regulatory bodies, as it deviates from normal banking practices where individuals generally have clear purposes for such transfers.

In contrast, the other options, while they might involve financial activity, do not inherently suggest illicit behavior. For example, engaging in frequent trading of stocks may indicate an active investment strategy rather than money laundering. Maintaining a consistent income stream from a job reflects standard employment and financial stability, which doesn't imply any wrongdoing. Similarly, utilizing savings over a long period is a common practice and not an indication of money laundering. Therefore, option C stands out as the most indicative behavior associated with money laundering activities.