Answer:
D - The slope from point O to point A is three times the slope of the line from point A to point B.
A, the interquartile range is 10, does not fit.
The interquartile range is found by subtracting the upper quartile and the lower quartile; in a box-and-whisker plot these are the outer edges of the box. In this case, they are 40 and 20; 40-20 = 20, not 10.