20) Consider a swapping system in which memory consists of the following memory-hole sizes in the following order: 10 MB, 4 MB, 20 MB, 18 MB, 7 MB, 9 MB, 8 MB, and 15 MB. Which hole is taken for successive segment requests of 12 MB, 10 MB and 9 MB if Best Fit algorithm is used? a. 15, 10, 9 b. 20, 18, 9 c. 18, 10, 9 d. 15, 20, 10 e. None of above