The mean and standard deviation (SD) of the heights (in centimeters) of four groups of...

This question tests understanding of standard deviation as a measure of variability. The group with thesmalleststandard deviation has the least variability. Comparing the values, Group 3 has the smallest SD at 6.9. Therefore, option D is correct. The mean does not affect variability; only the SD matters in this comparison. The NEX often includes questions where students must interpret statistical summaries rather than perform calculations. Remember that lower SD values indicate data points are more closely clustered around the mean.