def selection_phase(self) -> Tuple[Optional[State], Optional[str]]:
        """
        Select (state, rollout) with the highest score from candidate pool C.
        """
        selected_state, selected_rollout = self.C.pop()
        return selected_state, selected_rollout

        Select (state, rollout) with the highest score from candidate pool C.
        
data/omegaPRM_v2/omegaprm.py