A six digit number is formed by repeating a three digit number. For example 256256, 678678, etc. Any number of this form is divisible by

According to the question the number can be of form abcabc.

The general form of number abcabc is

Abcabc = 100000a + 10000b + 1000c + 100a + 10b + c.

Abcabc = 100000a + 100a + 10000b + 10b + 1000c + c.

Abcabc = 100100a + 10010b + 1001c.

Abcabc = 1001(100a + 10b + c).

Clearly we can see that abcabc is divisible by 1001 because 1001 is one of the factor of it.

∴ Option (d) is correct.