Which of the following materials is prohibited from entering U.S. commerce?

The correct answer is the category that includes obscene matter, as this material is specifically prohibited from entering U.S. commerce due to laws that aim to uphold moral standards and public decency. The prohibition against obscene matter is rooted in legal definitions that vary by jurisdiction but consider material as obscene if it meets specific criteria, such as being patently offensive and lacking serious literary, artistic, political, or scientific value.

In contrast, luxury goods, processed food items, and textiles may have certain regulations and restrictions associated with them, but they are not outright prohibited from entering U.S. commerce. Luxury goods may face tariffs or trade regulations, processed food items must comply with health and safety standards but are commonly imported, and textiles can be subject to quotas or specific manufacturing requirements but are typically allowed. Therefore, obscene matter stands apart due to its complete prohibition based on legislative acts aimed at protecting societal standards.