Concept: The question tests on the basics of Counting
Solution
For a number to be divisible by 5, the number should end with 0 or 5.
If the number ends with 0.
Since 5 has to be one of the numbers, 5 can be fixed in any of the 4 places in 4 ways.
We now have 8 digits. which can be arranged in 8 * 7 * 6 ways for the 3 remaining places.
Therefore the number of numbers ending with 0 = 4 * 8 * 7 * 6 = 1344
If the number ends with 5.
The first place can have any of the 8 digits (excluding 0 and 5), the second place can again have 8 digits (excluding the number in the 1st place but with 0 being a possibility). The 3rd and the 4th place can have 7 and 6 digits respectively.
The total numbers with 5 in the units place = 8 * 8 * 7 * 6 = 2688
The total such numbers = 1344 + 2688 = 4032
4032 = k * 4! = 24k
k = 4032 / 24 = 168
Option B