Which option is not considered one of the basic styles of roof?

The option that is not considered one of the basic styles of roof is the shoulder. In roofing terminology, the basic styles include gable, hip, and flat roofs, each representing a distinct structural design and set of characteristics.

A gable roof features two sloping sides that meet at a ridge, creating end walls with a triangular shape. This style is popular due to its efficiency in shedding water and snow, as well as its straightforward construction.

A hip roof, on the other hand, has slopes on all four sides that converge at a peak. This design provides greater stability against wind and weather, making it a preferred choice in many areas.

Flat roofs are characterized by their minimal slope and are often utilized in commercial buildings or modern architectural designs. While they pose some drainage challenges, they allow for the use of the roof space for recreational areas or equipment.

The term "shoulder" does not refer to a recognized roofing style in the context of traditional roof design. Thus, the omission of shoulder from the primary list of roofing styles underscores its lack of recognition in the industry compared to the other three, which are well-established and widely used methods of roofing.