(a) A county acting through its Quorum Court may exercise local legislative authority not denied by the Constitution or by law.
(b) No county may declare any act a felony or exercise any authority not relating to county affairs.
(c) A county may, for any public purpose, contract, cooperate, or join with any other county, or with any political subdivisions of the State or any other states or their political subdivisions, or with the United States.