What did the Fugitive Slave Act do?

Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the persons who have been, or may hereafter be, appointed commissioners, in virtue of any act of Congress, by the Circuit Courts of the United States, and Who, in consequence of such appointment, are authorized to exercise the powers that any justice of the peace, or other magistrate of any of the United States, may exercise in respect to offenders for any crime or offense against the United States, by arresting, imprisoning, or bailing the same under and by the virtue of the thirty-third section of the act of the twenty-fourth of September seventeen hundred and eighty-nine, entitled "An Act to establish the judicial courts of the United States" shall be, and are hereby, authorized and required to exercise and discharge all the powers and duties conferred by this act.

the answer would be d.