The correct answer is D
a polymer is a substance made up of large molecules with repeating sub units called monomers.
A is incorrect because its a ring structure which means it cannot form the long chain that is exhibited by polymers.
B is incorrect because the double bonds will cause saturation, hence no monomer can bond to another monomer to form the large molecule.
C is incorrect because the large molecule has repeating sub-units hence only specific types of molecules can be present, and it is usually carbon and hydrogen.
