What behavior is characteristic of carpet beetles?

Carpet beetles are known for their specific feeding habits, which primarily include consuming natural fibers such as wool, fur, silk, and even other types of animal hair. This behavior is characteristic of the larvae, which are the destructive stage of the insect. They may also feed on debris that contains these fibers, including hair and food spills, as well as any items made from animal products. The adult beetles are typically not the problem; instead, it's the larvae that pose a threat to materials in homes and businesses where these fibers are present.

While the other options involve various types of pests and their behaviors, they do not accurately describe the lifestyle and feeding habits of carpet beetles. Infesting stored grains is more typical of pests such as grain weevils. Building webs is characteristic of spiders, and causing structural damage is generally associated with wood-boring insects like termites. Therefore, option B accurately reflects the primary behavior of carpet beetles, making it the correct choice.