The clause in the United States Constitution that allows the federal government to create one currency for the country is known as "Common coinage."
This is evident in the fact that Article 1 section 8, clause 5.1 termed Coinage power stated that " To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;"
Hence, in this case, the correct answer is "Common coinage."
