Ms. Leeper gives her sixth- and seventh-grade students a geography test to decide who will represent her class in the school geography bee. The line plots below show the results of the test for her sixth-grade class and seventh-grade class, respectively. The data for each grade have the same interquartile range (IQR). Which of the following best compares the two test score distributions?

A - The median score of the seventh-grade class is 2 points greater than the median score of the sixth-grade class. This difference is the same as the IQR.

B - The median score of the seventh-grade class is 2 points greater than the median score of the sixth-grade class. This difference is twice as much as the IQR.

C - The median score of the seventh-grade class is 3 points greater than the median score of the sixth-grade class. This difference is the same as the IQR.

D - The median score of the seventh-grade class is 3 points greater than the median score of the sixth-grade class. This difference is twice as much as the IQR.