Polyvinyl chloride (PVC) is a synthetic polymer. Its full name indicates it is made from vinyl chloride monomers. The monomer must contain a carbon-carbon double bond to undergo addition polymerization and form the long polymer chain.

The correct monomer is vinyl chloride, which has the chemical formula: ${\mathrm{CH}}_2=\mathrm{CHCl}$. It is not chloroethane (a saturated compound with no double bond), ethylene (which would form polyethylene, not PVC), or tetrafluoroethylene (the monomer for PTFE, Teflon).

Final Answer: None of the above (The correct monomer is Vinyl Chloride)