Answer:
the answer would be A. a measure of center, such as the median
Step-by-step explanation:
A measure of center for a numerical data set summarizes all of its values with a single number, while a measure of variation describes how its values vary with a single number.
Some examples of a measure of center are median and mode. Some examples of a measure of variation are interquartile range and mean absolute deviation.
The salon manager wants one number to summarize all the values of the data set.