Which one of the following is a chain growth polymer?

The nucleic acid is synthesized when nucleotides are joined together by a condensation reaction by phosphate groups. In the case of protein and starch is formed by the condensation reaction with the release of water. Chain growth polymerization is a process by which the high molecular weight polymer is formed by the polymerization reaction. Polystyrene is synthesized by chain-growth polymerization. Here unsaturated monomer styrene is added to the active site which grows polymeric chain one at a time.