Monomers identified from copolymer repeating units

Steps:

• Analyze the polymer chain for two distinct repeating segments derived from alkene monomers.
• Match the first segment: a three-carbon unit with chlorines on adjacent carbons, indicating 1,2-dichloropropene as the source.
• Match the second segment: a four-carbon unit with a chlorine on the central carbon and a double bond position, indicating 2-chlorobut-2-ene.
• Verify copolymer formation via addition polymerization linking these monomers alternately.

Why A is correct:

• 1,2-Dichloropropene provides the -CHCl-CHCl-CH2- unit, and 2-chlorobut-2-ene provides the -C(CH3)Cl-CH=CH- unit, matching the polymer's structure per addition copolymerization rules.

Why the others are wrong:

• B: 2,3-Dichlorobutene has chlorines on carbons 2 and 3, not matching the three-carbon segment.
• C: Chlorobutene is too vague and lacks the specific double bond position for the four-carbon unit.
• D: Chloropropene lacks the vicinal dichlorides needed for the first segment.

Final answer: A