Which of the following polymers in thermosetting?

Bakelite is a thermosetting polymer. Explanation: Thermosetting polymers are those that undergo a chemical reaction when heated and become irreversibly hard and rigid. Bakelite, which is also known as phenolic resin, is a thermosetting polymer that is synthesized by the reaction of phenol and formaldehyde. Once the reaction is complete, the resulting material is in a hard, infusible state that cannot be melted or reshaped by heating. On the other hand, nylon, polypropene, and polystyrene are thermoplastic polymers, which can be melted and reshaped upon heating.