Final answer:
The Comptroller General of the United States is the head of the Government Accountability Office (GAO), which serves as the auditing and investigative arm of Congress, providing key oversight information. Option b.
Step-by-step explanation:
The Comptroller General of the United States is the head of the Government Accountability Office (GAO) option b. This agency provides Congress and the heads of executive agencies with auditing, evaluation, and investigative services. It is known for its nonpartisan and fact-based operation, often referred to as the "congressional watchdog". The GAO works diligently to supply Congress with information about the federal budget across a wide range of areas, including education, health care, and defense, among others. Additionally, it produces an annual performance and accountability report for Congress which details its own achievements and areas for improvement over the year.