Help me in solving NTMCQ3 problem

My issue

As we see in the example the factors for 18 are {1, 2, 3, 6, 9, 18},
similarly we can say for 8, {1, 2, 4, 8} they pair up perfectly, but why aren’t they in the solution?

Learning course: Introduction to Number theory
Problem Link: CodeChef: Practical coding for everyone

yeah u are right the correct answer would be 6,7,8,15