Final answer:
The correct answer is A) U-Channel, which is used for top and bottom plates in light gauge steel framing.
Step-by-step explanation:
The light gauge steel framing member typically used for top and bottom plates is called a U-Channel. The U-Channel is utilized due to its shape, which provides a stable base and top for the wall framing, allowing for secure attachment of wall sheathing, and being an effective member for distributing loads. Unlike an I-Beam, which is mentioned as a reference in construction for reducing bending strains, the U-Channel serves a different purpose in light gauge steel framing systems, primarily focused on non-load-bearing structures or as part of the detail in load-bearing systems.