For the same random sample of 20 respondents, health is measured according to a 4-point scale: 1 = excellent, 2 = good, 3 = fair, and 4 = poor. Four social classes are reported here: lower, working, middle, and upper. What is the F-obtained Statistics?
a) 3.75
b) 2.45
c) 5.5
d) 4.25