The branches of state government are established by

a. the us constitution.
b. a state’s constitution.
c. the citizens of a state.
d. a state’s governor.

The correct option is B.
The affair of a county is directed by the constitution of the country while the affair of a state is directed by the state's constitution. Each state in the United States of America has its own constitution. The state's constitution is the document which lays down the governmental structures, the political processes and the limitation to the use of power by the state.