The polymer, which can be stretched and retains its original status on releasing the force is

Polymers are those chains that are held together by the weak intermolecular forces. These weak forces provides ability to stretch the polymer. 

Vulcanized rubber are those polymers that have ability to stretch and retains its original position once forces releases. Buna – N is a synthetic rubber which can be stretched by applying force and retains its original status on releasing the force.