What is the name of the rigid conduit service entrance that extends through the roof of single-story houses?

The correct answer is "Mast." A mast is a rigid conduit that is commonly utilized in the service entrance of single-story houses, extending vertically through the roof. It serves as a support structure for electrical service drops from overhead wires to the building. The mast ensures that the electrical connections are kept secure and protected from environmental elements, providing a pathway for the electrical cables to enter the structure safely.

In contrast, options like "Cap" and "Pole" do not typically refer to components directly involved in service entrance applications. "Pipe" is a broader term and could pertain to various types of conduit or piping, but it lacks the specificity of "mast" in the context of electrical service entrances. Thus, "Mast" is the term that accurately describes the component serving this specific function.