Which letter represents the upper quartile of the data set on the box plot?
B
C
D
E

The upper quartile is the same as the third quartile (Q3). The value of Q3 is the right edge of the box.
Extra info: The left edge is the lower quartile, or Q1 (first quartile). The median is the vertical line inside the box. The min and max are the left-most and right-most tips of the whiskers (points A and E respectively)