Which of the following regulates hiring and testing of 90% of federal bureaucrats through a written examination administered by the Office of Personnel Management?

The civil service system is the correct answer because it is the framework that governs the hiring and employment practices for the majority of federal government employees. This system was established to ensure that hiring practices are based on merit rather than political connections or arbitrary decisions. The Office of Personnel Management (OPM) plays a key role in this process, administering written examinations that help assess the qualifications of candidates for federal positions.

The civil service system seeks to promote efficiency and fairness in the federal workforce by emphasizing standardized testing and evaluation processes. This structure not only aims to attract qualified individuals but also helps maintain accountability within federal agencies. Therefore, the reference to 90% of federal bureaucrats being regulated through this system underscores its significance in managing human resources within the federal government.

Other options do not accurately reflect the specific framework and its responsibilities related to federal hiring and testing practices, highlighting why the civil service system is the correct choice.