Polystyrene via Addition Polymerization Steps:

• Identify monomer as styrene (C6H5-CH=CH2) with a reactive vinyl group.
• Recognize addition polymerization opens the C=C double bond to form chains without byproducts.
• Confirm polystyrene's structure: repeating [-CH2-CH(C6H5)-] units from styrene linkage.
• Rule out condensation, which requires functional groups like -OH or -COOH for small molecule elimination.

Why B is correct:

• B pairs addition polymerization with the accurate partial structure of polystyrene, matching the vinyl addition mechanism.

Why the others are wrong:

• A: Addition type correct, but likely shows incorrect partial structure (e.g., wrong linkage).
• C: Condensation incorrect; styrene lacks groups for elimination reactions like water loss.
• D: Condensation incorrect and partial structure mismatched for polystyrene.

Final answer: B