What is the required pitch for dry system main piping per NFPA 13?

The correct answer reflects the requirements set forth by NFPA 13 regarding the installation of dry system main piping. According to NFPA 13, the required pitch for dry system main piping must be designed to facilitate the drainage of water and prevent the accumulation of moisture, which can lead to corrosion or other system failures.

A pitch of 1/2 inch per 10 feet ensures that any condensation or residual water that may collect in the pipes can adequately flow toward the drain points, thereby maintaining the integrity and functionality of the dry system. This slope helps ensure that the dry system remains operable and serves its purpose effectively, even in the presence of any moisture.

The other options represent different pitches that do not meet the NFPA's specified requirements for dry systems, which may lead to potential issues with water accumulation and subsequent malfunctions of the sprinkler system.