For state and local governments, State of, County of, and City of are a. often included for clarity. b. an important unit in the name. c. not included in the indexed name. d. always included in the indexed name

a. often included for clarity

Explanation:

The name state and the country and the city are given by the local governments and the governments of the state are differentiated. The basis of the clarity of the names and as to make a distinction in as for important units, hence they are thus kept separate often for the purpose of the clarity.