The correct answer is Silk.

Key Points

• Silk is a natural polymer. 
• Natural polymers occur in nature and can be extracted.
  • Examples of naturally occurring polymers are silk, wool, DNA, cellulose and proteins, and rubber.
•  Natural polymers have been widely used in a variety of biomedical applications such as pharmaceuticals, tissue regeneration scaffolds, drug delivery agents, and imaging agents.
  • In wound care, they are used as dressings for acute or chronic wounds and as regeneration templates.
• Hence, option 2 is correct.

Additional Information

• Polymer :
  • A polymer is a large molecule or a macromolecule which essentially is a combination of many subunits.
  • Polymers may be naturally found in plants and animals (natural polymers) or maybe man-made (synthetic polymers).
  • Different polymers have a number of unique physical and chemical properties due to which they find usage in everyday life.
  • Polymers cannot be classified under one category because of their complex structures, different behaviours, and vast applications.
• Classification of Polymers :
  • Natural Polymers:
    • ​They occur naturally and are found in plants and animals.
    • To add up, we also have biodegradable polymers which are called biopolymers.
  • Semi-synthetic Polymers:
    • They are derived from naturally occurring polymers and undergo further chemical modification.
      • For example – cellulose nitrate, cellulose acetate.
  • Synthetic Polymers:
    • These are man-made polymers.
    • Plastic is the most common and widely used synthetic polymer.
    • It is used in industries and various dairy products.
    • For example – nylon-6, 6, polyethers.