The correct option is A Outlier: 40
Following the key, the data set of the given stem and leaf diagram is:
30,35,37,38,39,40,41,45,46,47,50,57,60,62,63
There are 15 values in the given data set. There are 7 values to the left of 45 and 7 values to the right of 45. So, the middle value of the data set is 45. Thus, the center of the data is 45.
The smallest observation in the plot is 30 and the largest observation in the plot is 63. So, the spread is from 30 to 63.
An outlier is a data value that is numerically distant from the data set or it is a value that is very different from the rest of the values in the data set. Here, 40 is very similar to the other data values. So, it is not an outlier.