Final answer:
The standard deviation of a set of test scores is a statistical measure that indicates the spread of the test scores from the mean.
Step-by-step explanation:
The best description of the standard deviation of a set of test scores is that it is a statistical measure that indicates the spread of the test scores from the mean. The standard deviation measures how far the individual test scores are from the average (mean) test score. It provides a numerical measure of the overall amount of variation in the data set. The larger the standard deviation, the more spread out the test scores are from the average.