Step 1: Understanding the Concept:
Polystyrene (from styrene, \(\text{C}_6\text{H}_5\text{CH=CH}_2\)) is a light, rigid, brittle thermoplastic that can be moulded easily or expanded into foam.
Step 2: Uses:
It is used for disposable cups, plates, packing material (thermocol) and insulation. Polypropylene is used for ropes and containers, PET for bottles and fibres, and HDPE for pipes and toys.
Final Answer:
The polymer is polystyrene, option (B).
\[ \boxed{\text{Polystyrene}} \]