Agency loans, also known as conforming loans, are typically residential loans that are securitized through entities like the Federal National Mortgage Association (FNMA), Government National Mortgage Association (GNMA), and Federal Home Loan Mortgage Corporation (FHLMC). These loans conform to the guidelines set by these government-sponsored entities (GSEs). The GSEs buy these loans from lenders, package them into mortgage-backed securities (MBS), and guarantee the timely payment of principal and interest to the MBS investors. This process helps to provide liquidity to the mortgage market, enabling lenders to make more loans. The FNMA, commonly known as Fannie Mae, is one of the leading agencies in this process.

Choice A is incorrect. Adjustable-rate mortgage loans are not typically securitized through the Federal National Mortgage Association (FNMA). While FNMA does deal with adjustable-rate mortgages, it is not the primary type of loan they securitize.

Choice B is incorrect. Non-agency loans are those that are not backed by government agencies. The Federal National Mortgage Association, being a government-sponsored enterprise, primarily deals with agency loans and does not typically securitize non-agency loans.

Choice C is incorrect. Jumbos or jumbo loans exceed the conforming loan limits set by the Federal Housing Finance Agency (FHFA), and hence, they are not usually securitized through FNMA which primarily deals with conforming loans within the set limits.