Which of the following types of reports should security guards be prepared to write?

Security guards are primarily tasked with ensuring safety and security within their assigned areas, and part of this responsibility includes documentation. The correct choice highlights the types of reports that are specifically relevant to a security guard's duties.

Incident reports are crucial as they document any unusual occurrences, breaches of security, or law enforcement interactions that took place during a shift. These reports must be clear, factual, and detailed to aid in investigations and provide a record of events. Daily activity logs offer a summary of the day’s events, helping supervisors understand what transpired during a guard's shift and ensuring accountability. Accident reports capture details of any injuries or property damage that occur, which is essential for liability and process compliance.

In contrast, customer satisfaction reports, financial expenditure reports, and marketing analysis reports are more aligned with business operations, client feedback, and economic assessments, rather than securing and monitoring property or individuals. Thus, the focus on incident reports, daily activity logs, and accident reports aligns directly with the security function a guard fulfills, making it the most relevant and correct answer.