Which of these is a disadvantage of synthetic fibres?

Options

A. They are very glossy
B. They melt very easily
C. They easily crush.
D. They have a short life span.

Explanation

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks for the disadvantages of synthetic fibres.

2. **Understanding Synthetic Fibres**: Synthetic fibres are man-made fibres produced from chemical substances. They are commonly used in textiles and other applications.

3. **List Common Disadvantages**:
- **Highly Flammable**: Synthetic fibres can easily catch fire, which poses a safety risk.
- **Low Melting Point**: Many synthetic fibres have a low melting point, meaning they can melt easily when exposed to heat.

4. **Selecting the Disadvantage**: From the listed disadvantages, both "highly flammable" and "low melting point" are significant. However, if the question provides options, we need to choose the one that is most commonly recognized as a disadvantage.

5. **Conclusion**: Based on the properties discussed, the correct answer to the question would be that synthetic fibres are highly flammable and have a low melting point.

**Final Answer**: The disadvantage of synthetic fibres is that they are highly flammable and have a low melting point.

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