Which types of welds are covered by AWS D1.1?

The correct response identifies fillet welds, groove welds, and plug or slot welds as types of welds covered by AWS D1.1. This code specifically addresses these types of welds because they are fundamental methods used in steel construction, each serving essential structural roles.

Fillet welds are commonly used in joints that require a strong connection between two pieces of metal, especially in corner and T-joint configurations. Groove welds offer deeper penetration and are crucial for joints where higher strength is necessary, typically used in butt joints. Plug and slot welds are utilized to connect components by welding through holes in one piece to the surface of another, providing effective attachment in certain assembly situations.

While the other options include various types of welds, they do not align as directly with the primary types explicitly covered in AWS D1.1. The focus on specific types like fillet and groove welds reflects their prevalence and importance in structural applications, making them essential for compliance with the code.