The back-to-back stem-and-leaf plot below shows exam scores from two different math classes. what is the mode and mean for class a and the range and median for class b?

a. mode class a = 1
mean class a = 59.4
range class b = 50
median class b = 77
b. mode class a = 61
mean class a = 59.4
range class b = 54
median class b = 78
c. mode class a = 59
mean class a = 56.5
range class b = 54
median class b = 90
d. mode class a = 1
mean class a = 56.5
range class b = 52
median class b = 80