The right answer is <span>the light saturation point.
More light usually results in higher photosynthesis levels. However, with the increase of the intensity of the light, the photosynthesis rate eventually reaches a maximum point. This point is called "luminous saturation point".
When this point is reached, the intensity of the light does not increase the rate of photosynthesis and the rate of photosynthesis curve ceases to increase.
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The best answer would be "research reasons why species change over long periods of time"
if not i apologize but this is my best guess<span />
I think it is NAD, this ensures that the NAD can go back to glycolysis where it can again be reduced and go back through anaerobic respiration.