Which of these characteristics of synthetic fibres is a disadvantage to us?

Options

A. Cost
B. Elasticity
C. Tensile strength
D. High flammability

Explanation

**Step-by-Step Solution:**

1. **Understanding Synthetic Fibres**: Synthetic fibres are man-made fibres created through chemical processes. They have various characteristics that can be advantageous or disadvantageous.

2. **Evaluating Options**: We need to evaluate the characteristics of synthetic fibres given in the options to determine which one is a disadvantage.

3. **Cost of Synthetic Fibres**: The first option mentions the cost. Synthetic fibres are generally low in cost, which is an advantage, not a disadvantage.

4. **Elasticity of Synthetic Fibres**: The second option discusses elasticity. Synthetic fibres have high elasticity, which is beneficial for their use in clothing and other applications. This characteristic is also an advantage.

5. **Tensile Strength of Synthetic Fibres**: The third option refers to tensile strength. Synthetic fibres like nylon have high tensile strength, making them durable. Again, this is an advantage.

6. **Flammability of Synthetic Fibres**: The fourth option addresses flammability. Some synthetic fibres, particularly polyester, are known for their high flammability, which means they can catch fire easily. This characteristic poses a safety risk and is considered a disadvantage.

7. **Conclusion**: Among the options evaluated, the high flammability of synthetic fibres is the characteristic that represents a disadvantage to us.

**Final Answer**: The high flammability of synthetic fibres is a disadvantage to us.

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