Final answer:
Within the bureaucracy, the U.S. Postal Service (A) has the largest number of civil employees.
Step-by-step explanation:
The agency within the bureaucracy that has the largest number of civil employees is A. U.S. Postal Service. The United States Postal Service (USPS) is described as a widely used government corporation that was once a cabinet department and is responsible for providing postal service in the U.S. Since its transformation into a government corporation in the early 1970s, the USPS operates more independently and seeks to be run more like a business. It is important to note that the USPS and the Department of Defense are recognized as the two federal entities with the most civilian employees.