The median
A)
1) Let's begin by ordering the data points from the least to the greatest one:
79 80 81 84 86 88 90 91 156
So let's now pick a measure of central tendency to summarize the data. Consider the following: there is no mode in this distribution for there are no repetitive data points.
2) So let's take the median and the mean, and then analyze it:
Since the mean is higher than almost all data points this is not a typical value in this distribution. So we can state that the answer is the median.