Answer:
Calculate the slope in the four intervals with the formula
m = (f(b) - f(a)) / (b - a) slope in Intervall [a; b]
m1 = (3 - 0) / (2 - 0) = 1.5
m2 = (11 - 3) / (4 - 2) = 4
m3 = (23 - 3) / (6 - 2) = 5
m4 = (23 - 11) / (6 - 4) = 6
between x = 4 and x = 6 is the correct answer.