The correct answer is D) A class 2 fit is looser than a class 4 fit. The different "class of fit" for machine threads on bolts and nuts refers to the tolerance between the mating parts. A class 2 fit has a wider tolerance range, allowing for more play between the bolt and nut, resulting in a looser fit. In contrast, a class 4 fit has a tighter tolerance range, leading to a more precise and secure fit between the bolt and nut. The other options are incorrect because: A) A class 1 fit does not necessarily have fewer threads per inch, as the class of fit is determined by the tolerance range, not the thread count. B) A class 1 fit is not always tighter than a class 2 fit, as it depends on the specific tolerance ranges. C) A class 4 fit does not always have more threads per inch, as the class of fit is not directly related to the thread count.