Which of the following is true about copolymerisation?

• A. radical, coordination, anionic, or cationic polymerization, depending on the type of initiation
• B. addition of monomer to a metal complex, propagation is by successive insertion of monomer at the metal, and termination occurs when the metal complex separates from the polymer
• C. monomers react by eliminating small molecules like H2O, NH3, CH2O and NaCl in a repetitive manner, Indefinite growth of the polymer occurs at both ends
• D. a mixture of more than one (or different) monomeric species is allowed to polymerize