Which of the following is NOT a lululemon proprietary fabric?

The correct choice highlights that spandex is not a lululemon proprietary fabric, as it is a commonly used synthetic fiber in the textile industry. Spandex, also known as elastane, is widely used by many brands for its exceptional elasticity, helping garments stretch and conform to the body.

In contrast, Luxtreme, Nulu, and Everlux are all unique, proprietary materials developed specifically by lululemon. Luxtreme is known for its lightweight, supportive, and moisture-wicking properties, ideal for high-intensity workouts. Nulu offers a soft, buttery feel for yoga and casual wear, designed for comfort and to provide an ultra-lightweight experience. Everlux combines the benefits of softness, breathability, and sweat-wicking, making it well-suited for intense training. Each of these fabrics represents lululemon's commitment to innovative performance wear tailored for active lifestyles.