___________ : when the value of a nation's currency is allowed to fluctuate according to the foreign exchange market.

AGold standard
BFixed exchange rate
CCurrency calculation
DFloating exchange rate

Verified Answer :

It would be a "Floating exchange rate" that occurs when the value of a nation's currency is allowed to fluctuate according to the foreign exchange market, since it is thought to "float" along the ebbing and flowing "tides" of the market.