Answer: c. in the U.S. demand for loanable funds and the supply of dollars in the market for foreign-currency exchange.
Step-by-step explanation:
Bonds are a type of loanable funds which are issued to gain access to cash for certain activities. Both countries and companies do this. When the U.S. government issues bonds, they do so taking into account the amount of funds they would need to fund what it is they want to funds.
They also do so taking into account, the amount of dollars needed by in the foreign-currency exchange market so that they can pump enough dollars into the world economy.