Answer: B. fifth deciles
Explanation: Deciles are groupings of data that are each made up of 10% of the data points. The median is the central tendency measure, which is the middle value of the data set and thus lies in the fifth deciles.

The median is the middle value when a set of values is arranged from smallest to largest. It is used to measure the central tendency of a data set. In deciles, the median is measured by the fifth decile, which is the value that divides the data set into two equal parts, with half of the values below it and half of the values above it. This value is also known as the 50th percentile. The median is the most common measure of central tendency, as it is not affected by outliers or extreme values in the data set.