There are two kinds of polymers : addition polymers and condensation polymers
In case of addition polymers, there is simple addition of unsaturated monomeric units. example: polythene
While in case of condensation polymers, the monomers combine with the elimination of a small molecule like H2O, HCl, NH3 etc.
So here as there is formation of H2O as product there is formation of a polymer and that too a condensation polymer
Example: condensation polymer of diamine and dicarboxylic acid to form a polyamide (Nylon-6,6)
Answer: condensation
formation of polymer