Which of These Statements Correctly Describes Active Hyperaemia

Which of these statements correctly describes active hyperaemia?

A) It refers to the arteriolar dilation that occurs within a tissue in response to local chemical changes that accompany increased metabolic activity of that tissue.
B) It refers to local arteriolar mechanisms that are aimed at keeping tissue blood flow constant in spite of wide deviations in mean arterial driving pressure.
C) It refers to the increase in blood flow to a tissue that occurs after removal of an occlusion of its blood supply.
D) It is important in maintaining an adequate pressure head to drive blood forward into a tissue.