In terms of fabric properties, which of the following would be best described as "non-static"?

The best choice for describing a fabric property as "non-static" is an antistatic finish. An antistatic finish is applied to fabrics to reduce or eliminate the buildup of static electricity. This is particularly important in environments where static discharge can be hazardous, such as in certain electronic manufacturing settings or for certain types of clothing worn in controlled environments. By neutralizing electric charges that can accumulate on the surface of the fabric, antistatic finishes help ensure that garments do not attract dust or cling to the body, offering a more comfortable wearing experience.

In contrast, a cotton finish generally relates to the enhancement of the cotton fabric's appearance, texture, or performance, but it does not specifically address static properties. Flame-retardant finishes are designed to make fabrics resistant to ignition and burning, which does not pertain directly to static properties. Water-repellent finishes provide a barrier to moisture but similarly do not influence how fabric behaves concerning static electricity. Thus, the antistatic finish is specifically designed to make fabric non-static and is the clear answer in this context.