To maintain compliance with safety standards, barriers must be made of what type of materials?

Barriers in indoor places of assembly are crucial for maintaining safety and managing crowd control, and thus they must be constructed from suitable and durable materials. This ensures that they can withstand the various stresses and strains they may encounter, such as contact from people, environmental factors, or accidental impacts.

Using suitable materials means that they meet specific safety standards and regulations, ensuring that they are effective in preventing accidents and delineating spaces. Durability is equally important; barriers must remain functional over time without degrading or failing, which is vital in maintaining a safe environment for occupants.

Other options suggest less appropriate materials, either indicating a lack of standards or implying that the materials may not be effective in a safety context. This reinforces why the emphasis is on using suitable and durable materials to comply fully with safety standards and protect all individuals within the assembly area.