The correct answer is: "to coin money and regulate the value thereof, as well as that of foreign coin, and to fix the standard of weights and measures "
The National Bank has the role of printing a single currency that is valid in all of the states and it also serves as a place where the government can store its money and withdraw it when necessary.
With the printing of money, the bank was the power of regulating its value, as an increase on the supply will consequently represent a decrease in the value of it as there is an excess in the market. This surplus or deficit in the money supply also affects foreign currencies as the exchange rate varies.