Answer: B)
There are 7 different letters in the word 'ABOLISH'.
Therefore,
The number of arrangements of any 4 out of seven letters of the word = Number of all permutations
of 7 letters, taken 4 at a time =
nPr = n(n - 1)(n - 2) ... (n - r + 1)
Here, n = 7 and r = 4, then we have
7p4 = 7 x 6 x 5 x 4 = 840.
Hence, the required number of ways is 840.