A number is divisible by 11, if the difference between the sums of digits in even places and the sum of digits in odd places is either 0 or divisible by 11.
In option (a), the digit in even place is 1 and digits in odd places are 1 and 1.
And their difference is (1 + 1) -1 = 1.
1 is not divisible by 11.
So, 111 is not divisible by 11.
In option (b), the digit in even place is 9 and digits in odd places are 4 and 5.
And their difference is ( 4 + 5) -9 = 0.
The difference is 0.
So, 594 is divisible by 11.
In option (c), the digit in even place is 2 and digits in odd places are 2 and 2.
And their difference is ( 2 + 2) -2 = 2.
2 is not divisible by 11.
So, 222 is not divisible by 11.
In option (d), the digit in even place is 1 and digits in odd places are 8 and 5.
And their difference is (8 + 5) -1 = 12.
12 is not divisible by 11.
So, 815 is not divisible by 11.
Therefore, option (b) is correct.