Answer D is correct. : it expanded the federal court system.
Until this Act, state courts
had a bigger share of the federal juristiction. The Judiciary Act
strengthened the federal court.
The Answer B is wrong, since it is, in a way, the
opposite of D.
To understand the reason for rejecting the other answers, some context is needed:
The Judiciary Act of 1801 is also known as the Midnight Judges Act, because it was passed during the last days of the presidency of John Adams, a Federalist, when it was already known that the next president would be Thomas Jefferson, a Democratic Republican. Adams was accused of trying to fill the judgeships created with this act with fellow Federalists. Thus the asnwer A is wrong: the opposite was true, as this act increased judgeships for Federalists, not Republicans. Therefore it was also not opposed by the Federalists (but the Democratic Republicans (so answer C is wrong).