Explanation:

Let's analyze the sum of the numbers:

- The numbers are represented as:

- abc = 100a + 10b + c

- cab = 100c + 10a + b

- bca = 100b + 10c + a

- Their sum is:

- (100a + 10b + c) + (100c + 10a + b) + (100b + 10c + a)

- Combining like terms, we get: 111a + 111b + 111c

- This simplifies to 111(a + b + c)

- Now let's check divisibility:

- 111 is clearly divisible by 1 and 3.

- 111 is not divisible by 31.

- 111 is obviously divisible by a + b + c, as the entire expression is multiplied by it.

Correct Answer: Option 3, 31