Through penetrations in concrete floor assemblies can have the annular space filled with mortar if the penetrating item is?

The correct answer pertains to the requirements for fire stopping and sealing through penetrations in concrete floor assemblies. When a metallic pipe penetrates a concrete floor assembly, the annular space around the pipe can be filled with mortar. This is due to the properties of metallic materials, which can maintain the integrity of fire-rated assemblies when properly sealed with materials such as mortar. The use of mortar is particularly effective in reducing smoke and flame passage through these penetrations, adhering to fire prevention codes.

For the other options, such as plastic pipes, flexible conduit, and non-metallic conduit, they typically have different requirements primarily due to their material properties and behaviors under fire exposure, leading to different sealing methods or materials. These items may require the use of specific fire stop systems that are different from mortar in order to meet fire safety standards.