An organization experiencing staff shortages wants to contract a temporary employee to assist with work...

Comprehensive and Detailed Explanation:

The three-way match (A) is the most effective control to ensure that services have been received and align with both requisition and invoicing. For temporary employees, this means verifying that hours worked or services provided match the purchase requisition and that an invoice is only paid if supported by documentation of services received.

Option B (management approval) ensures authorization but not service completion.

Option C provides clarity but is not a control for verifying actual work.

Option D ensures budgetary compliance but does not prevent overpayment for unperformed services.

Thus, the strongest control is Option A, ensuring validity, accuracy, and completeness of vendor payments.