Which of the following is a safety device that keeps a slotted nut from turning or coming off?

Answer: C — Cotter pin

The correct choice is a cotter pin, which serves as a safety device that secures a slotted nut to prevent it from loosening or spinning off during operation. Cotter pins are made of metal and are typically used in conjunction with a nut that has a slot or hole designed specifically for this purpose. When a cotter pin is inserted through the hole in the nut and then bent at the ends, it effectively locks the nut in position, providing a reliable means of preventing accidental disassembly of critical components. This safety feature is essential in various mechanical assemblies where vibration or movement could cause a nut to loosen over time. By securing the nut in place, cotter pins enhance the integrity and safety of the assembly. Other options such as a lock tab act to secure the nut as well, but they generally do so by being bent into place without needing a hole, while a snap ring is primarily used in grooves to retain components rather than securing nuts. Thread pitch describes the distance between threads on a screw or bolt, rather than serving a safety function. Therefore, while these other devices have their places in mechanical assemblies, the cotter pin is specifically designed to prevent a slotted nut from turning or coming off, making it the correct answer in this