@Arjun sir, here all the answers have made the assumption that for MRU the pages 101 to 120 will be swaped out. Can we make assumptions like this in exam? Because in this case Optimal will not behave exactly like MRU, and the reason is the twenty pages that were already loaded. Please note here I have taken the sequence as 1,2,3,.....99,100,1,2,3......99,100,1,2,3.....99,100.
Please correct me if I am wrong, according to my calculations, in Optimal we will get 40/300 page hit rate, and in MRU we will get 0/300 Page Hit Rate.
I know MRU and Optimal work exactly same when the sequence is in a loop but in this question, the twenty frames are already loaded and that is what is making the difference.