Let me put like this;
Light , CO2, Temperature are the main limiting factors that matter in the exams
When light increases the rate of photosynthesis increase until a certain point when photosynthesis evens off
This is because the 2 other factors; amount CO2 or the temperature will not support (not sure if that's a good word) a higher rate of photosynthesis. The same is true for any of the 3 factors where one factor no longer supports the a higher rate of photosynthesis and has now become the limiting factor
Hope that helps