When mortgages are sold after they have been funded, they are considered part of the:

The primary mortgage market refers to the initial stage of mortgage lending, where borrowers obtain loans directly from lenders. In this market, mortgages are originated and funded, but not sold. Therefore, it does not encompass the buying and selling of previously funded mortgages, which occurs in the secondary market.

The Rural Housing Service is a government agency that supports homeownership in rural areas by providing loans and grants for housing development. While it plays a vital role in certain housing markets, it does not pertain to the sale of existing mortgages, making it an incorrect choice in this context.

The Federal Reserve System is the central banking system of the United States, responsible for monetary policy and financial stability. While it influences the mortgage market through interest rates and economic policy, it does not directly deal with the buying and selling of mortgages, which is the function of the secondary mortgage market.