Choice "C" is correct. The foreign country's exports will be less expensive for the United States since it will require fewer U.S. dollars to buy the foreign goods. If the conversion factor is 1.5 FCU to the USD, it takes $.666 to purchase one currency unit. When the conversion factor changes to 1.7 FCU to the USD, it takes $.588 to purchase one currency unit. Therefore, with the higher exchange rate the country's exports will be less expensive for the United States.
Choice "d" is incorrect. The currency has depreciated.
Choice "a" is incorrect. Imports of U.S. goods are less affordable. It will now require 1.7 units rather than the old 1.5 units to purchase every dollar of the same U.S. goods.
Choice "b" is incorrect. The currency of the foreign country will be able to buy fewer U.S. dollars per unit as a result of the change in the exchange rate.