JEE Advanced 2016 · Paper 1, Chemistry question 23

Natural rubber. It is cis-1,4-polyisoprene, $\ce{-[CH2-C(CH3)=CH-CH2]_n-}$.

Hydrogenation. Saturating the double bond gives
$$\ce{-[CH2-CH(CH3)-CH2-CH2]_n-},$$
which is the same chain as an alternating copolymer of ethylene ($\ce{-CH2-CH2-}$) and propylene ($\ce{-CH2-CH(CH3)-}$).

(A)