American Association of Family and Consumer Sciences (AAFCS) Practice Test

The correct answer is woven from the nature of wool as a natural fiber. Wool is well-known for its soft texture and heat resistance, coming from the fleece of sheep and other animals. One of the characteristics of wool is its tendency to shrink when subjected to heat and moisture during the washing process. This phenomenon, known as "felting," occurs because the scales on wool fibers interlock more tightly when agitated in water, leading to a reduced size of the fabric.

Flax, while a natural fiber that can exhibit some level of shrinkage, is primarily known for its durability and strength, rather than a pronounced tendency to shrink significantly when washed. Synthetic blends typically do not undergo significant shrinkage due to their engineered properties designed to withstand various conditions, including washing. Silk, while also a natural fiber, has different care requirements and tends to retain its shape better than wool when washed. Thus, the notable aspect of wool's shrinkage under washing conditions makes it the correct answer.