With which size of reinforcing bar is a welder qualified using #8 (#25) bar allowed to weld?

The correct choice indicates that a welder qualified using #8 reinforcing bar is permitted to weld #8 and larger bars. In welding qualifications, the size of the reinforcing bar that a welder is authorized to weld is linked to the size for which they have demonstrated proficiency. Since #8 is the size to which the welder has been qualified, they can work with bars of this size and any larger sizes.

This means that the welder's skills are considered adequate for performing welds on reinforcing bars within that specified range. The qualifications established during training and testing allow for flexibility in terms of the sizes of bars that may be welded, so any reinforcing bar larger than #8, such as #9, #10, or larger, falls within the capabilities of the welder.

It's essential for welders to understand the implications of their qualifications to ensure they adhere to safety and structural integrity standards in welding applications.