ANSWER
C. -6
EXPLANATION
The rate of change is the change in the dependent variable when the independent variable changes 1 unit. In this case, all columns in the table have a change in the x variable of 1, so the difference between each column in the y-row is the rate of change,
[tex]m=-9-(-3)=-15-(-9)=-21-(-15)=-6[/tex]Hence, the rate of change is -6.