If i put a * next to a word and i use that same word again, do i put the symbol next to the other word too?

Which statement is not true about run-on sentences? a. a run-on sentence has more than one clause. b. one way to correct a run-on sentence is to add a joining word c. one way to correct a run-on sentence is to add an appropriate punctuation mark. d. a run-on sentence has only one clause.