Identifying Monomers from Copolymer Structure Steps:

• Examine the polymer chain for alternating or sequential repeating units derived from alkene monomers.
• Identify carbon chain lengths and chlorine positions in each unit to match monomer backbones.
• Match double bond positions in monomers to single bonds in the polymer, confirming addition polymerization.
• Compare substituent patterns (e.g., Cl on specific carbons) to eliminate mismatched options.

Why A is correct:

• 1,2-Dichloropropene (CH2=CCl-CH2Cl) and 2-chlorobut-2-ene (CH3-CCl=CH-CH3) form units with a 3-carbon chain bearing Cl on C1-C2 and a 4-carbon chain with Cl on C2, matching the copolymer diagram via addition across double bonds.

Why the others are wrong:

• B: 2,3-Dichlorobutene lacks standard naming; chloropropene alone can't form the butene-derived unit.
• C: 2,3-Dichlorobut-1-ene has Cl on adjacent carbons in a 4-carbon chain, mismatching the propene unit's structure.
• D: Chloropropene and 2-chlorobut-1-ene both have terminal double bonds, but fail to replicate internal Cl positions in the polymer.

Final answer: A