c) Consider the page-reference string from t = 1 until t = 20, as shown in Fig. 1(c). Assume that there are four frames available and that they are all initially empty. 1 2. 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 a b d b e f b b g C i a h f i d e Fig. 1(c). Sample of Page Address Stream i. Show the frame allocation for each of the following page replacement policies: First-in- first-out, optimal, and least recently used. (6 marks) ii. Discuss and analyze the best policy by finding each policy's relative performance concerning page faults. (2 marks) iii. Design a strategy to reduce the number of page faults. (2 marks) iv. At t = 15 to t = 20, Frame l's protection bit is set to 1, i.e., it cannot be replaced. Show the page replacement using first-in-first-out. (2 marks)