Concept:Thermosetting plastics, once moulded, cannot be softened by reheating. Thermoplastics can be repeatedly softened and reshaped on heating.Explanation:Bakelite and melamine are both thermosetting plastics. They harden permanently during moulding and do not melt again when heated. Instead, they decompose if heated further. Thermoplastics such as polythene and PVC soften on heating and can be remoulded. Option A incorrectly calls Bakelite a thermoplastic. Option B incorrectly calls melamine a thermoplastic. Option C claims both are thermoplastics, which is false. Only option D correctly states that both Bakelite and melamine are thermosetting plastics.Answer:D. Bakelite and melamine are both thermosetting plastics.