Step 1: Concept Polymers can be classified based on their source: Natural, Semi-synthetic, or Synthetic.
Step 2: Meaning Natural polymers are those found in nature, specifically in plants and animals.
Step 3: Analysis Cellulose is the primary structural component of the cell wall of green plants. Teflon, PVC, and Neoprene are all man-made (synthetic).
Step 4: Conclusion Cellulose is a naturally occurring polysaccharide polymer.
Final Answer: (A)