What Is Characteristic of the Process of Step-Growth Polymerization

What is characteristic of the process of Step-Growth Polymerization?
I. In the beginning of the polymerization process, there are many oligomers (an oligomer is made from a few monomers, its chain length is short) .
II. High macromolecular weights are only reached at the very end of the polymerization process.
III. If two bifunctional monomers (e.g. diamine and dicarboxylic acid) are used, slight deviations from 1:1 stoichiometry will prevent high macromolecular weights at the end of the polymerization process.
IV. Polymer chains can grow individually to high macromolecular weight at any time during the polymerization process.

A) I and II
B) II and III
C) I, II and III
D) II and IV