Thank you for the opportunity to help you with your question!
The answer is B: has been inferred from the power to legislate.
Explanation: No provision of the Constitution expressly authorizes either House of Congress to make investigations. The Court has long since accorded its agreement with Congress that the investigatory power is so essential to the legislative function as to be implied from the general vesting of legislative power in Congress. “We are of the opinion,” wrote Justice Van Devanter, for a unanimous Court, “that the power of inquiry—with process to enforce it—is an essential and appropriate auxiliary to the legislative function.
Please let me know if you need any clarification. I'm always happy to answer your questions.