Given the following psuedocode, what value of GRADENUM can be input to output a grade of "B"?
Start
Read GRADENUM
CASENTRY GRADENUM
CASE 90 <= GRADENUM <= 100
GRADE = "A"
CASE 80 <= GRADENUM <= 90
GRADE = "B"
CASE 70 <= GRADENUM <= 80
GRADE = "C"
CASE 60 <= GRADENUM <= 70
GRADE = "D"
CASE other
GRADE = "F"
ENDCASE
Write GRADE
Stop
a. 80
b. 90
c. less than 80
d. greater than 90