The rate of cellular respiration is regulated by its major product, ATP, via feedback inhibition. As the diagram shows, high levels of ATP inhibit phosphofructokinase (PFK), an early enzyme in glycolysis. As a result, the rate of cellular respiration, and thus ATP production, decreases. Feedback inhibition enables cells to adjust their rate of cellular respiration to match their demand for ATP. Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?
a) ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production. b) ATP levels would rise at first, decreasing the inhibition of PFK and increasing the rate of ATP production. c) ATP levels would fall at first, increasing the inhibition of PFK and increasing the rate of ATP production. d) ATP levels would rise at first, increasing the inhibition of PFK and increasing the rate of ATP production.