______ is one of the measures of central tendency.

Statistical measures used to summarise a data set fall into two broad categories: measures of central tendency — Mean, Median, and Mode — which locate a single representative or "central" value around which the data clusters, and measures of dispersion — Range, Average (Mean) Deviation, Variance, and Standard Deviation — which describe how widely the data values are spread out from that centre.

The median of a data set is the value that occupies the middle position when the observations are arranged in ascending (or descending) order — for an odd number of observations it is the single middle value, and for an even number it is the average of the two middle values. Because it directly locates the centre of the arranged data, the median is classified as a measure of central tendency.

Checking this classification against the other options:

• Range is the difference between the maximum and the minimum observation in the data set — it quantifies spread, not the centre.

• Average deviation is the average of the absolute differences of each observation from the mean, so it measures how scattered the data is, not its centre.

• Standard deviation is the square root of the variance (the mean of squared deviations from the mean); like variance, it measures spread, not the centre.

Since Range, Average Deviation, and Standard Deviation all describe dispersion while only the median identifies the centre of the data set, Median is the measure of central tendency among the four options given.