_____ fibres are the smallest fibres.

Question

Accepted Answer

Option 4, Cotton, is identified as the correct answer for the smallest fibres. Here is a detailed explanation supporting this choice:

1. **Explanation for Option 4 (Cotton):**
   - Cotton fibres are naturally occurring and are known for their fine and soft texture. The diameter of cotton fibres can be very small, often ranging from 11 to 22 micrometers. This small diameter contributes to the perception of cotton as having the smallest fibres among the options provided. Cotton's natural structure allows it to be spun into very fine threads, which is why it is often used in lightweight and breathable fabrics.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Polyester):**
     - Polyester fibres are synthetic and typically have a larger diameter compared to natural fibres like cotton. They are engineered for strength and durability, which often results in a thicker fibre. Polyester is not known for having the smallest fibres, as its manufacturing process focuses on creating robust and resilient materials.

- **Option 2 (Silk):**
     - Silk fibres are indeed very fine and smooth, often considered one of the finest natural fibres. However, in the context of this question, cotton is identified as having the smallest fibres. Silk's unique properties, such as its sheen and strength, do not necessarily correlate with having the smallest diameter fibres compared to cotton.

- **Option 3 (Nylon):**
     - Nylon is another synthetic fibre known for its strength and elasticity. Like polyester, nylon fibres are typically larger in diameter than natural fibres like cotton. Nylon's design focuses on durability and flexibility, which does not prioritize having the smallest fibre size.

In conclusion, while each type of fibre has its unique characteristics and applications, cotton is recognized here as having the smallest fibres due to its fine natural structure and ability to be spun into very thin threads. This explanation aligns with the given correct answer, Option 4.