Which one of the following statements is not true?

Question

$\begin {array} {1 1} (a)\;\text{ Natural rubber has Trans configuration at every double bond}\\ (b)\;\text{ Buna –s is a copolymer of butadiene aandstyrene} \\ (c)\;\text{ Natural rubber is 1-4 polymer of isoperene}\\ (d)\;\text{ Vulcanisation is the process of formation of sulphur bridfes between different chains} \end {array}$