Which of the following, if true, suggests the conclusion above is not necessarily valid? A. There was a greater number of students in the 2011 class than in the 2012 class. B. The percent of students who received 'A's in 2011 was less than in 2012. C. Five more students received 'A's in 2012 than in 2011. D. The same number of students received 'B's in 2011 as in 2012. E. The percent of students who received 'B's was greater in 2012 than in 2011.