Which of the following would increase the current account of Country X? Country Y is Country X's sole trading partner.

a) Inflation increases in countries X and Y by comparable amounts. Country X's and Country Y's currencies depreciate by the same amount.

b) Country X imposes tariffs on imports from Country Y, and Country Y retaliates by imposing an identical tax on X's exports.

c) The central banks of Country X and Country Y reduce the money supply to increase interest rates.

d) Country X imposes a quota on imports, and Country Y retaliates by imposing an identical quota on X's exports.