Question

Which of the following belong to thermoplastics?                  

1. Natural resins

2. Phenol formaldehyde

3. Polystyrene

4. Poly vinyl chloride

(a) 1, 2, 3 and 4             (b) 1, 2 and 3 only

(c) 1, 3 and 4 only          (d) 2, 3 and 4 only