Which of the following is used to describe data variability?

The standard deviation is the correct answer because it quantifies the amount of variation or dispersion of a set of data points in relation to the mean. It gives insight into how much the individual data points differ from the average value, providing a clear measure of variability. A larger standard deviation indicates greater variation among the data points, while a smaller standard deviation signifies that the data points are closer to the mean.

In contrast, the mean serves as a measure of central tendency, giving only the average but not addressing how spread out the data is. Skewness measures the asymmetry of the data distribution but does not capture the extent of variability itself. The median is another measure of central tendency that indicates the middle value of a dataset but, like the mean, does not provide information about how much the data values differ from each other. Thus, the standard deviation is specifically designed to describe the variability of data in a way that the other options are not.