Scrapie is (a). . . . . . . .

Scrapie is a Progressive fatal disease of CNS.
Scrapie is a fatal, degenerative disease affecting the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), and as such it is thought to be caused by a prion.
Scrapie and other transmissible spongiform encephalopathies are caused by prion disease. Prions were determined to be the infectious agent because transmission is difficult to prevent with heat, radiation and disinfectants, the agent does not evoke any detectable immune response, and it has a long incubation period of between 18 months and 5 years.