we have two 4 bit numbers, then for comparing we have to calculate all 8 bits from both numbers.
There fore total Combinatnions of i/p will become = 22*4 = 256.
It is known that, there are 24 combinations for which the bits are equal,
then remaining combinations are equally divided in which A > B and A < B.
Therefore remaining combinations are 256 - 16 = 240.
Since there are equal number of combinations for A > B and A < B,
then number of combinations for which A > B = 240 / 2 = 120.
Hence A is correct.
In General,
If there are two n bit numbers, then
there are 2n combinations for which numbers are equal, and
A > B ,combinations will be = 22n - 2n / 2
Please correct me if i am Wrong.