Final answer:
The minimum depth for burying pipes depends on various factors including the diameter of the pipe and local regulations. The newer rule of thumb suggests a minimum of 15 pipe diameters deep, which requires more specifics to provide an exact figure.
Step-by-step explanation:
The minimum depth for the burial of piping and tubing is not directly specified in the information provided, but we can make an analytical approach. The rule of thumb mentioned suggests a depth that's related to the diameter of the pipe in question. If using the newer suggestion of burying at least 15 diameters deep, for a pipe with a certain diameter, we can calculate the corresponding minimum burial depth. However, without the actual diameter of the pipe in question, we cannot firmly choose an answer from the options A) 18", B) 20", C) 15", or D) 24".
Moreover, additional context such as local regulations, type of piping material, environmental conditions, and the substance being transported in the pipes can influence the appropriate depth for burial. Therefore, it's crucial to consult the local building codes or standards to determine the exact minimum burial depth required for a particular application.