All of the examples listed below, with one exception, are public goods which at times might possibly lose some of their public good properties due to congestion. Which example is an exception?

	A.	A large urban nonprofit hospital.
	B.	A small nonprofit clinic for homeless people funded by a charitable organization.
	C.	Emergency departments of county-run hospitals.
	D.	Discoveries made through medical research.
	E.	A chain of free methadone clinics in a large city