What is the reasoning behind setting the upper and lower control limits +30; from the mean? A. The limits of the Z table are set at +303 B. We know that 99.73% of assignable variation is contained within 30j, and thus any data point outside of the limits is likely due to natural variation C. We know that 99.73% of natural variation is contained within 307, and thus any data point outside of the limits is likely due to assignable variation D. 95.45% of the time, the sample averages will fall within + 30, if the process has only natural variation