Which of the following is an example of a synthetic fiber?

Acrylic is an example of a synthetic fiber because it is made from polymers that are produced through chemical processes, specifically polymerizing acrylonitrile. This synthetic process allows acrylic fibers to exhibit properties such as lightweight, warmth, and moisture-wicking capabilities, which make them suitable for a variety of applications, particularly in textiles and clothing.

In contrast, the other options represent natural fibers derived from animals or plants. Wool is produced from sheep and is a natural protein fiber. Silk is obtained from the cocoons of silkworms and is also a natural protein fiber. Linen is made from the flax plant and is a natural cellulose fiber. These natural fibers are not synthesized through chemical processes, which is what distinguishes them from synthetic fibers like acrylic.