Which of the following is an example of a one-sided tolerance for length?

The correct example of a one-sided tolerance for length is represented by the option that specifies a limit only in one direction from a nominal value. In this case, 3.254" +0.002" -0.000" indicates that the nominal dimension of 3.254 inches can increase by a maximum of 0.002 inches, but there is no allowance for it to decrease below 3.254 inches.

One-sided tolerances are often used in applications where only an increase is acceptable while ensuring that the dimension does not fall below a specific minimum value. This is crucial in situations where parts must fit within a given assembly or maintain specific functional characteristics without risking insufficiencies.

Other options present either symmetrical tolerances or variations that allow for deviations in both directions from the nominal value. For instance, option B allows for both positive and negative deviations (±0.003"), which makes it a two-sided tolerance. Options C and D, while different in their allowance, also don't provide just a one-sided specification, making them unsuitable comparisons for one-sided tolerances.