For combustible penetrating items in nonfire-resistance-rated assemblies, the maximum number of stories they can connect is:

In nonfire-resistance-rated assemblies, combustible penetrating items are limited in their ability to connect multiple stories to reduce the risk of fire spread. This limitation helps ensure that if a fire were to occur, its progression from floor to floor would be more contained, thus enhancing the overall safety and integrity of the building. By restricting these connections to a maximum of two stories, the intent is to minimize the potential for fire to travel vertically through these combustible materials.

Connecting more than two stories could lead to increased risks during an incident, as flames and smoke could propagate more easily throughout the structure. Building codes are designed to prioritize life safety, and this particular restriction is part of a broader strategy to manage fire hazards associated with the use of combustible materials in construction. Therefore, the correct answer reflects an understanding of fire safety principles and building code requirements.