It seems that this exercise has an assumption that is not really spelled out. It seems that the Kripke structure should be cleared from any finite paths at first, and then the question should be answered. That means that you should repeatedly remove all deadend states (those having no outgoing transitions) unless no more deadend states remain. Then, you should read the initial states, reachable states, etc. from the states that are left. If I am right with this, we should really change the exercise questions as I wrote here.
