4. Page Replacement (30 points) A computer has four page frames. The time of loading, time of last access, and the R bit for each page are as shown below (the times are in clock ticks): Last ref 280 265 270 285 Page Loaded 126 230 140 110 (a) Which page will FIFO replace? (b) Which page will LRU replace? (c) Which page will second chance replace? Briefly explain your answers to get full credit