What is the reasoning behind setting the upper and lower control limits + 30- from the mean? X A. 95.45% of the time, the sample averages will fall within + 30- if the process has only natural variation X B. We know that 99.73% of natural variation is contained within 1302, and thus any data point outside of the limits is likely due to assignable variation X C. We know that 99.73% of assignable variation is contained within + 30-, and thus any data point outside of the limits is likely due to natural variation X' D. The limits of the Z table are set at + 30- X