The correct answer is option 1: because of the air encapsulated between two layers. When two layers of a cloth are used, there is a small amount of air trapped between the layers. Air is a poor conductor of heat, meaning it does not easily transfer heat. This trapped air acts as an insulator, preventing heat from escaping and keeping the body warm. The air pocket acts as a barrier between the body and the outside environment, reducing heat loss.

Option 2 is not correct because the effective thickness of the cloth is not the primary reason for it being warmer. It is the air encapsulated between the layers that provides the insulation.

Option 3 and option 4 are incorrect because the fabric and weaving technique of the cloth do not directly contribute to its insulating properties. The key factor is the air trapped between the layers. However, the choice of fabric and weaving may indirectly affect the warmth of the cloth by influencing its ability to hold air and retain heat.