What kind of fabric is described as having a weave where the fibers lie parallel and are tightly woven?

Worsted wool is accurately described as having a weave where the fibers lie parallel and are tightly woven. This type of fabric is typically produced from long-staple wool fibers that are combed to align the fibers in one direction, resulting in a smooth texture and a durable, closely woven finish. This technique produces a fabric that is not only strong but also has a refined appearance, making it ideal for garments that require both formality and longevity.

In contrast, while mohair fibers have their own unique properties, they do not specifically emphasize a tightly woven structure in the same way that worsted wool does. Mohair is known for its luster and resilience but is typically not described in terms of a parallel fiber weave. Alpaca fleece, on the other hand, is soft and warm but has a loftier texture compared to the tightly woven plane of worsted wool fabrics. Silk fabric, while luxurious and smooth, is characterized by its own specific weave types, such as satin or chiffon, rather than the tight, parallel structure exemplified by worsted wool. Thus, the specific characteristics of worsted wool clearly set it apart as the correct answer.