The correct option is B 21
We express 1056 in terms of 23 using Euclid's division lemma which states that given positive integers a and b, there exist unique pair of integers b and r such that
a=bq+r.
Here, we take a=1056 and b=23.
Also, 1056=23×45+21.
As we can observe, 1056−21 is divisible by 23.
∴ On subtracting 21 from 1056, the resultant is divisible by 23.