A file of 32768 blocks is to be sorted with an available buffer space of 256 blocks. ( 5 points) (a) How many passes will be needed in the merge phase of the external sort-merge algorithm? (10 points) (b) Calculate the number of disk block reads and writes before sorting of the whole file is completed (5 points) (c) Calculate the worst-case number of disk block reads and writes with minimum number of main memory buffers of 3 before sorting of the whole file is completed ( 5 points)