a file consists of eight logical blocks, a through h, and is open for sequential access. the current position is at the beginning of block e. the following operations are performed: read block d, read block f, delete block e, insert new block c' between c and d. (a) for each of the four disk block allocation schemes, contiguous, linked, using fat, and indexed, determine which blocks must be read from and written to the disk to perform each of the four operations.