Answer:
D
Step-by-step explanation:
The average rate of change of f(x) in the closed interval [ a, b ] is
[tex]\frac{f(b)-f(a)}{b-a}[/tex]
Here (a, b ] = [ 1, 3 ], thus
f(b) = f(3) = 5 ← from graph
f(a) = f(1) = - 3 ← from graph
average rate of change = [tex]\frac{5-(-3)}{3-1}[/tex] = [tex]\frac{8}{2}[/tex] = 4 → D
