Which of the following is classified as a permanent fastener?

A permanent fastener is one that, once installed, cannot be easily removed without damaging either the fastener itself or the materials being joined. In this context, rivets are classified as permanent fasteners because they are typically installed by deforming the materials that hold them in place, creating a strong bond that is not meant to be disassembled.

Rivets are often used in applications where a solid and enduring connection is required, such as in aircraft construction and heavy machinery. When installed, a rivet is generally not designed to be removed, which ensures a high level of security and stability in the assembly.

In contrast, nails and screws can usually be removed and reused, making them less permanent. Clips are often designed for quick assembly or disassembly, which also means they do not fit the criteria for permanence. Thus, rivets are unique in their intended use as permanent fasteners within this group of options.