Final answer:
The agency not specializing in mortgage securitization is Sallie Mae, whereas both Freddie Mac and Fannie Mae are government-sponsored enterprises that deal with this process.
Step-by-step explanation:
The agency referred to in the question is a governmental entity that specializes in mortgage securitization, which is the process of pooling various types of mortgage loans and selling the consolidated debt as securities to investors. The correct answer to the question - which of the following is not a government-sponsored agency that specializes in mortgage securitization? - is c. Sallie Mae. This is because Freddie Mac (Federal Home Loan Mortgage Corporation) and Fannie Mae (Federal National Mortgage Association) are well-known government-sponsored enterprises that specialize in this area. In contrast, Sallie Mae (Sallie Mae Bank or formerly the Student Loan Marketing Association) primarily provides student loans and does not specialize in mortgage securitization.