Repeat unit molar mass matches monomer and enables chiral centers Steps:

• Divide polymer molar mass by number of repeat units to find repeat unit Mr: 112000 / 2000 = 56 (consistent with typical problem values for this setup).
• In addition polymerization, repeat unit Mr equals monomer Mr.
• Compute monomer Mr using atomic masses (C=12, H=1, Cl=35): A=62, B=76, C=56, D=90.
• Verify chiral center in repeat unit -CH2-CHR-: the CHR carbon has H, R, and two distinct polymer chain segments if R ≠ H.

Why C is correct:

• CH2=CHCH2CH3 (C4H8) has Mr=56, matching repeat unit; per IUPAC definition, the -CH(CH2CH3)- carbon is chiral with four different substituents (H, ethyl, left chain, right chain).

Why the others are wrong:

• A: Mr=62 ≠56.
• B: Mr=76 ≠56.
• D: Mr=90 ≠56.

Final answer: C