___ construction uses body parts welded together to form an integral frame.

Unibody construction is a method that integrates the body and frame into a single structure. In this design, various body panels and components are welded together to create a cohesive unit that enhances structural integrity, reduces weight, and improves safety. This construction technique allows for better handling and performance since the entire vehicle's frame provides a solid foundation for the suspension and other systems.

Unibody construction contrasts with other methods like body-on-frame, where the body is mounted onto a separate frame, allowing for easier repairs and modifications but often resulting in a heavier vehicle. Semi-unitized construction combines aspects of both unibody and body-on-frame designs, but it does not fully weld the body parts into a singular structure. Platform construction refers to a modular system used primarily in manufacturing multiple vehicle types using the same base architecture, which is not directly related to the integral nature of unibody designs.