A tissue culture of vertebrate muscle tissue was provided with a constant excess supply of glucose under anaerobic conditions and the amount of pyruvic acid and ATP were measured. The solid line in the graph above represents the pyruvic acid formed due to enzymatic reactions. ATP levels were also found to be highest at points A and C, lowest at B and D. A second culture was set up under the same conditions, except that substance X was added, and the results are indicated by the dotted line. B D 02468 10 12 14 16 18 20 22 24 26 28 30 32 34 Time (min) Which of the following best accounts for the shape of the solid line between points A and D? O After ten minutes the cellular enzymes were denatured. O Respiration cannot be controlled by the enzymes at the temperature indicated. O ATP acted as an allosteric inhibitor on one or more enzymes. O The cells required more glucose than what was provided. Rate of Pyruvic Acid Formation (moles/liter/min)