Which rivet accurately fits the conical depression made by a 100° countersink?

A 100° countersink is designed to accommodate a specific type of rivet known for its matching angle. When a conical depression is created at a 100° angle, it allows for a rivet that has the same angle in its head to fit perfectly. The correct rivet will have a head designed to match this angle, ensuring a flush and secure fit that also distributes load evenly across the surface.

In this case, the rivet associated with the 100° countersink is often referred to as a "flat-head" rivet, which has a wider and shallower profile that conforms to the counterbore. This design enhances compliance with structural and aerodynamic requirements in sheet metal applications.

Other options may refer to different rivet head designs, such as round or oval heads, which would not provide the same fit or structural integrity when seated in a 100° countersink. The emphasis on the specific angle and the shape of the rivet head is critical for ensuring proper installation and performance in applications that involve sheet metal structures.