What type of aluminum sheet requires a rivet 5/16 inch in length for joining?

The correct choice indicates that aluminum sheets with a thickness of 0.032-inch and 0.064-inch would require a rivet that is 5/16 inch in length for proper joining. This is due to the need to account for the total thickness of the materials being joined when selecting a rivet length.

In general, when riveting, it's essential to ensure that the rivet penetrates through all layers being joined while also allowing for adequate grip. For materials with a combined thickness like 0.032-inch and 0.064-inch, the total thickness would be 0.096 inch which necessitates a rivet length that ensures a solid connection without excessive protrusion.

Using a 5/16 inch rivet effectively covers this thickness while providing sufficient engagement in the joint, which is crucial for maintaining structural integrity in aircraft and other applications where sheet metal joinery is involved. This aligns with industry standards for rivet selection based on material thickness, ensuring a secure and reliable assembly.

In contrast, other thickness combinations listed would either require shorter rivets or may not provide the necessary grip for the rivet to function as intended. Hence, the specific combination in the correct answer is appropriate for the given rivet length.