Which of the following is true when comparing the different "class of fit" for machine threads on bolts and nuts?

Correct Answer: Option D — A class 2 fit is looser than a class 4 fit.

Thread classes define the tolerance and allowance of a fit. Class 1 represents a loose fit for quick assembly, while Class 4 represents a very tight, precision fit. Therefore, a Class 2 fit, which is standard for most bolts, is significantly looser than a high-tolerance Class 4 fit.