Given :
am × bn = 144145 where a > 1 and b > 1.
We can also write 144 as 24 × 32
Therefore, am × bn = 144145 that can be expressed as am × bn = (24 × 32)145
= 2580 × 3290
As we know that 3290 is a natural number, which implies that it can be expressed as a1, where a > 1
Therefore, the least possible value of m is 1.
By the same logic, the largest value of n is 580.
So, the largest value of (n - m) = (580 - 1) = 579
Therefore, the correct option is (A) : 579.