Question 511General Subjects - Assistant Engineer

The correct answer is D. The figure labeled D is not suitable for use as a hex head set screw. Hex head set screws are designed to be tightened and loosened using a hex wrench or allen key. The figure D illustration shows a slotted head, which is not compatible with a hex wrench and would not be appropriate for use as a hex head set screw. The other figures (A, C, and L) illustrate hex head designs that would be suitable for use as hex head set screws, as they can be properly engaged and tightened/loosened with a hex wrench tool.