Which fabric technology does Uniqlo use in its HEATTECH clothing line?

Uniqlo's HEATTECH clothing line is specifically designed to enhance warmth by utilizing a unique blend of materials that generate and retain body heat. This fabric technology is engineered to not only trap the warmth produced by the body but also to convert moisture into heat, thereby providing thermal insulation without the bulkiness of traditional winter clothing. This innovative combination keeps the wearer warm and comfortable during colder seasons.

The other options do not accurately describe the technological features of HEATTECH. While a blend of cotton and polyester might be common in various clothing lines, it does not convey the specific heat-generating capabilities that HEATTECH is known for. Similarly, a single-layer thermal fabric may offer some insulation but lacks the advanced functionality of the HEATTECH technology. Lastly, fabric made entirely of wool may provide warmth, but it does not incorporate the same moisture-wicking and heat-retaining innovations that define HEATTECH.