Which statement about the vulcanisation of natural rubber with sulfur is correct?

1. ASulfur adds to every double bond and gives a saturated linear polymer
2. BSulfur converts cis-polyisoprene into trans-polyisoprene
3. CSulfur gives a thermoplastic which becomes soft and sticky at lower temperature than raw rubber
4. DSulfur forms cross-links between chains at the reactive allylic sites near the double bonds, which increases hardness and tensile strength