Consider a system using preemptive priority scheduling with multiple real-time and user-level processes. Priority inheritance protocol is implemented.

I.. Priority inversion can occur when a low-priority process holds a resource that a high-priority process needs.

II. Under priority inheritance, the low-priority process temporarily inherits the higher priority to avoid blocking.

III. Priority inversion can be completely avoided if all processes are scheduled in a round-robin fashion.

IV. Starvation may still occur for low-priority processes even with priority inheritance.

Which of the statements are correct?