Polyacrylonitrile (C3H3N)n is vinyl polymer and derivative of acrylate family of polymer.The commercial name of polyacrylonitrile is Orlon therefore option (ii) is the correct answer.

Above is the diagram of polyacrylo nitrile.

Above is the diagram of Dacron.

Above is the diagram of Bakelite.

Above is the diagram of PVC.

is the commercial name of polyester.PVC is the thermoplastic polymer and bakelite is thermosetting therefore options (i),(iii),(iv) are incorrect.