Question

elimination
substitution
addition polymerization
condensation polymerization

Explanation:

In addition polymerization, monomers with double - bonds break the double - bond and add together to form a polymer. Here, ethene ($C_2H_4$) with a carbon - carbon double - bond forms polyethylene by adding together, without the loss of any small molecules. Elimination reactions involve the removal of atoms or groups to form a double - bond or triple - bond. Substitution reactions replace one atom or group with another. Condensation polymerization involves the formation of a polymer along with the elimination of small molecules like water.

Answer:

C. addition polymerization