S9, S10, S11 are deadend states. hence, you removed them from the initial states in step a). Since S8 is not a deadend (it has transitions, e.g. to S4), you did not remove this one from the initials. As the said states S8, S9, S10, S11 do not have incoming edges, their only way to be reachable is being initial. Therefore, S8 is the only one among the four that is left reachable.