Step 1: Concept
Polymers are large molecules composed of repeating subunits called monomers. Natural polymers are those found in nature, while synthetic polymers are man-made.
Step 2: Meaning
Cellulose is a natural polymer found in the cell walls of plants. Nylon-6, PVC (Polyvinyl Chloride), and Teflon are all synthetic polymers produced through chemical processes.
Step 3: Analysis
Option A: Cellulose - This is derived from plant cellulose, which is naturally occurring.
Option B: Nylon-6 - This is a synthetic polymer made by condensation of hexamethylenediamine and adipic acid.
Option C: PVC (Polyvinyl Chloride) - This is also a synthetic polymer formed by the polymerization of vinyl chloride monomer.
Option D: Teflon - Chemically known as polytetrafluoroethylene, it is another synthetic polymer.
Step 4: Conclusion
The natural polymer among the given options is cellulose.
Final Answer: (A)