Final answer:
Option a) Farmer Mac is the correct answer.
Step-by-step explanation:
The agency that does NOT issue agency discount notes among the options given is Farmer Mac (FAMC). Agency discount notes are short-term debt securities that are issued by government-sponsored enterprises (GSEs) such as Fannie Mae (FNMA), Sallie Mae (SLMA), and Freddie Mac (FHLMC).
These notes are typically used to raise short-term funds and are sold at a discount from their face value. On the other hand, Farmer Mac primarily deals with agricultural financing and does not engage in issuing these types of debt instruments.