Suppose that we have main memory using the local Least Recently Used (LRU) replacement scheme and the One-Block-Lookahead (OBL) prefetching scheme. OBL prefetching is also known as prefetch-on-a miss because virtual page i+1 is prefetched when we have a page fault on virtual page i. We assume that 4 page frames are allocated to a process, and the process references its virtual pages in the following order: 7, 5, 8, 6, 9, 5, 7. Illustrate the change in the LRU stack for each reference, and clearly describe how the LRU and OBL prefetching work together for each reference (to make the change in the LRU stack)