Which statement distinguishes step-growth (condensation) polymerisation of adipic acid and hexamethylenediamine from chain-growth addition polymerisation?

1. AThe growing chain carries a radical that adds to the next monomer
2. BA high molar mass is reached only when the functional groups have reacted to a very high conversion, because oligomers couple with each other throughout the reaction
3. CHigh-molar-mass chains are formed from the start while most of the monomer is still unreacted
4. DOnly monomer molecules add to the growing chain end, one at a time