The grades on a statistics exam for a sample of students are as follows: Stem Leaf 3 68 1278 156789 22457888 1156799 1246 14 If A + = 90%-100% A = 80%-89% B+ = 75%-79% B =70%-74% C+ =65%-69% C = 60%-64% D+ =55%-59% D =50%-54% F = 0-49% What is the most common letter grade earned? Multiple Choice F (0-49%) C (60%-64%) B (70%-74%) A (80%-89%) O D (50%-54%)