From the Civil War until 1914, what change(s) occurred in U.S. policie

From the Civil War until 1914, what change(s) occurred in U.S. policies regarding tariffs?

(a) Tariff rates were generally higher and customs receipts were higher than before the
Civil War.
(b) As the momentum of the westward movement increased, increased revenues from land sales allowed Congress to return tariff rates to their pre-Civil War levels.
(c) Customs revenues increased because of economic growth and the lack of important changes
in tariff policy.
(d) All of the above

ANSWER

(a)