Which of the following objects has the most structural strength?

Steel possesses the most structural strength due to its unique combination of high tensile strength and ductility. Tensile strength refers to the material's ability to resist being pulled apart, while ductility indicates its capability to deform without breaking. Steel’s molecular structure allows it to carry heavy loads and resist bending or breaking under stress, making it an ideal material for construction, machinery, and many other applications that require strength and durability.

In contrast, other materials like wood, plastic, and glass, while useful in various applications, do not match steel's overall strength characteristics. Wood can be strong, but its strength can vary significantly based on species, grain direction, and moisture content. Plastic generally has lower strength and can deform under heat or excessive load, and glass, while strong in compression, is brittle and prone to breaking under tension or impact. Therefore, steel stands out as the superior material considering structural strength in most construction and engineering scenarios.