Step 1: Understanding the Concept
We need a polymer in which all the hydrogen atoms of the monomer have been replaced by fluorine.
Step 2: Teflon
Teflon is made by polymerising tetrafluoroethylene, \(\text{CF}_2\text{=CF}_2\):
\[ n\,\text{CF}_2\text{=CF}_2\to[\text{-CF}_2\text{-CF}_2\text{-}]_n \]
There is no hydrogen in the chain, so it is fully fluorinated.
Step 3: Others
PVC is polyvinyl chloride and has chlorine. Neoprene is based on chloroprene and has chlorine. Buna-S is a copolymer of butadiene and styrene with no fluorine.
Final Answer:
Teflon is built from \(\text{CF}_2\text{=CF}_2\) and is fully fluorinated, option (B).
\[ \boxed{\text{Teflon}} \]