Which body can Congress use to investigate an agency?

Congress has the authority to use legislative hearings to investigate an agency. This process allows Congress to gather information, scrutinize the actions and decisions of federal agencies, and hold them accountable for their functions and policies. Legislative hearings are structured sessions where members of Congress can question agency officials, expert witnesses, and sometimes the public, to gain a deeper understanding of issues related to specific agencies.

Conducting these hearings is a vital aspect of Congress's oversight responsibilities. It enables lawmakers to ensure that agencies are operating effectively, adhering to laws, and using public funds appropriately. Through public hearings, the findings are often accessible to the general public, promoting transparency in government operations.

In contrast, the other options do not fit within the framework of Congress's formal investigatory powers in this context. Judicial inquiries pertain to the court system, which handles legal proceedings rather than legislative oversight. Executive commissions might investigate specific issues but do not have the same standing or authority as legislative bodies in terms of accountability. Public polls can gauge opinions but do not provide a formal mechanism for investigation or oversight of agencies.