If the natural tolerance of a process was reduced, which one of the following would have changed?

When the natural tolerance of a process is reduced, the primary impact is on the process variation. Natural tolerance refers to the inherent variability present in a process under stable conditions. This variability influences how far the actual output may deviate from the desired outcomes.

Reducing the natural tolerance typically indicates a tighter control on the process, resulting in a decrease in the amount of variability seen in process outputs. This means the process becomes more consistent and predictable, allowing for outputs to fall closer to the target or desired mean.

While the mean of the process, the specification limits, and the target may also play roles in how a process is assessed, those elements remain unchanged by simply reducing the natural tolerance. The specification limits define the acceptable range of outputs, and the target denotes the optimal output. Therefore, a direct change resulting from reduced natural tolerance is the variation in the outputs of the process, which is why this choice is the correct answer.