Which clothing material continues to provide warmth even when it is wet?

Introduction / Context:
This question tests basic science and everyday life awareness about fabrics and their thermal properties. When a person is caught in rain or snow, some materials lose insulation quickly, while others still provide warmth. Understanding which material keeps the body warm even after getting wet is important for health, outdoor safety and practical clothing choices in cold and damp climates.

Given Data / Assumptions:

• Four common clothing materials are listed: cotton, wool, nylon and silk.
• The question asks which of these materials keeps a person warm even when wet.
• No numerical data or formulas are needed, only conceptual understanding of insulation.

Concept / Approach:
Thermal insulation of clothing depends on how much air the fabric can trap and how it behaves when soaked with water. Wool fibres have a natural crimp and structure that trap a lot of air. Wool can absorb moisture while still retaining trapped air pockets, so it continues to insulate. Materials such as cotton tend to hold water and lose insulating air spaces, which makes them feel cold and heavy when wet.

Step-by-Step Solution:
Step 1: Consider how each fabric behaves when wet: cotton, wool, nylon and silk. Step 2: Remember that cotton absorbs water and becomes heavy and cold against the skin. Step 3: Recall that wool fibres trap air and can absorb moisture while still feeling relatively warm. Step 4: Nylon and silk are smooth synthetic or natural filaments that do not trap as much insulating air once wet. Step 5: Conclude that wool is the only option that provides significant warmth even in a wet state.

Verification / Alternative check:
Outdoor safety advice for hiking, mountaineering and camping frequently recommends wool or specialised synthetic layers instead of cotton in cold wet conditions. Phrases such as cotton kills highlight that cotton loses insulation when wet, while wool socks and sweaters are preferred for warmth. This real life guidance matches the scientific behaviour of the fabrics and confirms wool as the correct answer.

Why Other Options Are Wrong:
Cotton: Absorbs water easily, loses trapped air and quickly feels cold on the skin, so it does not keep a person warm when wet.
Nylon: Dries relatively fast but its thin, smooth fibres do not provide much warmth in a soaked state.
Silk: Comfortable and light but not designed for strong insulation when wet, especially in cold weather.

Common Pitfalls:
Learners sometimes choose cotton because it is widely used in clothing and is comfortable in dry conditions. Others may pick nylon, assuming that synthetic fibres are always better in all situations. The key idea is to focus specifically on warmth in a wet condition, where wool clearly outperforms the other materials due to its unique fibre structure and ability to trap air.

Final Answer:
Wool is the clothing material that still provides warmth even when it is wet.