# Which of the following compounds are formed by step-growth polymerisation?

$\begin{array}{1 1}(a)\;\text{Polyethylene}\\(b)\; \text{Teflon}\\(c)\;\text{ Orlon}\\(d)\;\text{Polyamides}\end{array}$

Polyamides have amide linkages in the chain.These polymers have one or more monomers and are condensed to form polymers.
E.g:-Nylon-66,Nylon-6
Hence (d) is the correct answer.