A few materials are listed in the box.
i) Nylon      ii) Acrylic       iii) Terylene     iv) Cotton     v) Wool    vi) Melamine     vii) PET
Which of the following represents a correct statement about these materials

(ii) is a good substitute for wool and (iii) is a good substitute for silk 

(iv) and (v) are natural polymers

(iii) and (i) are polyesters while (vii) is a polyamide

(vii) is a thermosetting plastic while (vi) is a thermoplastic