When a central bank intervenes into the foreign exchange market to set a country's exchange rate over long periods of time, it is called?

The answer is a fixed exchange rate. When a central bank interferes into the foreign exchange market to fix or adjust a nation’s exchange rate in a long period of time. A fixed exchange rate or also known as pegged exchanged rate, is defined as a type of exchange rate management wherein a currency’s value is fixed, hence the name, against the value of another distinct currency, or to an abundant of other currencies, or in another measurement of value.