5. Assume that a process has four page frames. The time of the last loading of a page, the time of last access to the page, and the reference (R) and modify (M) bits for the page are shown below. The times are in clock ticks. Page frame Page Time loaded Time referenced R M FO P15 132 284 1 F1 P18 273 296 0 F2 P17 210 315 0 1 F3 P16 247 279 1 1 Consider each of the following page-replacement algorithms and choose the page Pi to be replaced. Please answer with page number Pi. DO NOT use the frame number Fi. Explain your answer to receive full credit. (15%) (a) Least-recently-used (LRU) replacement algorithm (3%) (b) Second-chance replacement algorithm (4%) (c) Enhanced second-chance replacement algorithm (4%) (d) Optimal replacement algorithm (use the page reference string: P13, P17, P16, P17, P18, P15, P18, P16, P17, P15, P18, P15; decide the victim page when P13 is requested) (4%)