What is a good source of information for investigations concerning regulations of common carriers in interstate commerce?

The Interstate Commerce Commission (ICC) is the correct choice because it was specifically established to regulate the railroads and later expanded to include other forms of interstate transportation, including trucking and shipping. The ICC's primary role was to ensure that common carriers complied with the regulations governing their operations, which includes ensuring fair rates and service without discriminating against customers.

The ICC has historical importance in U.S. transportation regulation, overseeing the reliability, safety, and efficiency of interstate commerce that involves common carriers. This regulatory body provides a wealth of information on the statutes, rules, and precedents that inform investigations concerning the operations and regulatory frameworks surrounding common carriers.

While organizations like the Federal Bureau of Investigation, Bureau of Customs, and Federal Trade Commission have significant roles in law enforcement, customs regulation, and trade practices respectively, their focus does not directly encompass the specific regulations governing common carriers in interstate commerce. Hence, these agencies do not serve as dedicated sources for information in this area.