C
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, 2 ] , then
f(b) = f(2) = 2.5 ← value of y from graph
f(a) = f(- 1) = - 5 ← value of y from graph , then
average rate of change = [tex]\frac{2.5-(-5)}{2-(-1)}[/tex] = [tex]\frac{2.5+5}{2+1}[/tex] = [tex]\frac{7.5}{3}[/tex] = 2.5