(a) Nylon-6, 6 is the polymer of hexamethylene diamine and adipic acid. It is made by the condensation of given monomers. (b) Nylon-6 is also a condensation polymer of caprolactum. It is a polyamide. (c) Dacron is also a condensation polymer of ethylene glycol and terephthalic acid. It is an example of polyester. (d) Buna-S is an addition polymer of 1,3 , butadiene and styrene. Hence, only (d) is not a condensation polymer. ∴(d) is the correct option.