Final answer:
Fannie Mae is involved in mortgage financing by purchasing mortgages and then selling them as mortgage-backed securities, which consequently provides lenders with the necessary capital to offer more loans.
Step-by-step explanation:
Fannie Mae is directly involved in b) Mortgage financing. Fannie Mae, also known as the Federal National Mortgage Association, is a government-sponsored enterprise (GSE) that aims to ensure that mortgage markets function effectively and efficiently. It does this by purchasing mortgages on the secondary market, pooling them, and then selling them as mortgage-backed securities to investors on the open market. This process provides lenders with fresh capital to make new loans, which facilitates homeownership and affordability in the United States.