Identify cross linked polymer from following.

Step-by-step solution

The question requires identifying which polymer has a cross-linked structure from the given options. High density polythene (HDPE) is a linear polymer with high crystallinity and thermoplastic behavior, lacking cross-links. Low density polythene (LDPE) is highly branched but remains thermoplastic without cross-linking. Melamine refers to melamine-formaldehyde resin, a thermosetting polymer characterized by extensive cross-linking that forms a rigid, three-dimensional network structure, rendering it infusible upon h