Polyethylene terephthalate belongs to which class of synthetic polymer?

Polyester

The correct answer is option 3. Polyester.

Polyethylene terephthalate (PET) belongs to the class of synthetic polymers known as Polyester. PET is a type of polyester that is widely used for packaging materials, including plastic bottles for beverages and food items. Polyesters are a class of polymers with ester functional groups in their main chain, and PET is specifically classified as a thermoplastic polyester.