Which of the following is not a semisynthetic polymer?

1. Cis-polyisoprene

2. Cellulose nitrate

3. Cellulose acetate

4. Vulcanised rubber

HINT: These polymers are mostly derived from naturally occurring polymers by chemical modifications.
 
Cis-polyisoprene is not a semisynthetic polymer,
In practice polyisoprene is commonly used to refer to synthetic cis-1,4-polyisoprene, made by the industrial polymerisation of isoprene.
while the other three cellulose nitrate, cellulose acetate, and vulcanized rubber
 
are semisynthetic polymers made from cellulose, cellulose, and natural rubber respectively.
 synthetic polyisoprene are used primarily for tires.
 n1
2-Methyl-1,3-butadiene