The question is: **Which of the following polymerizes very easily?** Options: a) CH₂=CH-C≡CH b) CH₂=CH-CH=CH₂ c) CH₂=CH-CH₂-CH₂=CH₂ d) CH≡C-C≡CH ### **Correct Answer:** **b) CH₂=CH-CH=CH₂** **Explanation:** 1,3-Butadiene (CH₂=CH-CH=CH₂) polymerizes very easily to form polybutadiene, a common polymer. The presence of conjugated double bonds (alternating double and single bonds) in butadiene makes it highly reactive toward polymerization. Conjugated dienes are especially known for their ability to undergo addition polymerization. The other options either contain triple bonds (alkynes), which do not polymerize as easily, or have non-conjugated double bonds, which are less reactive in polymerization compared to conjugated systems. So, the answer is **option b**.