Through penetrations in fire-resistance-rated walls must be protected by what type of firestop system?

The correct answer is the approved penetration firestop system. This system is specifically designed to seal openings and penetrations in fire-resistance-rated walls, ensuring that the fire resistance of the wall is not compromised. These systems typically consist of materials that have been tested and approved for use in maintaining the integrity of fire-rated assemblies when subjected to fire conditions.

Using an approved penetration firestop system is critical because it minimizes the spread of fire and smoke through openings, which is essential for the safety of occupants and the preservation of property. The materials and methods used in these systems must be compatible with the fire rating of the wall they are protecting and adhere to the relevant building codes and standards.

The other types mentioned, while potentially relevant in different contexts, do not specifically denote the level of testing and approval required for fire-resistance-rated penetrations. Therefore, the approved penetration firestop system is the only appropriate choice for ensuring compliance and safety in these critical applications.