Which of the following polymer can be formed by using the following monomer unit?

1. Nylon-6,6

2. Nylon-2-nylon-6

3. Melamine polymer

4. Nylon-6

Hint: Used for making carpets, tire cords, parachutes, ropes, and industrial cords

The structure  of monomer is given, that is, caprolactam which on polymerization produces Nylon-6. The reaction is as follows: