Which type of vehicle construction uses a frame only in areas requiring extra support and a strong attachment point?

The correct answer is semi-unitized stub rail construction, which is a method of vehicle construction that combines aspects of both full-frame and unibody designs. In this approach, a frame is implemented only in specific areas that require additional strength, such as the rear or front sections, to provide robust attachment points for various components.

This design allows for a reduction in weight compared to a traditional full-frame vehicle while still offering the necessary rigidity and support where it is most needed, like mounting the suspension or absorbing impact during collisions. The use of strategically placed frame sections offers a compromise between the advantages of a full-frame design and the efficiency of a unibody structure.

In contrast, full-frame construction involves a complete separate frame underpinning the vehicle, which can lead to increased weight. Pseudo-unibody construction and monocoque construction typically involve integrating the body and frame into a single unit, which can distribute stress more evenly but does not provide the same localized strength as seen in semi-unitized stub rail construction.