The graph shows how the rate of photosynthesis in a crop plant changes with carbon dioxide concentration at a constant temperature and light intensity.

At which range of carbon dioxide concentration is carbon dioxide concentration not the limiting factor for photosynthesis, and how is this region represented mathematically?
From 0.14%0.14\%0.14% to 0.20%0.20\%0.20%; carbon dioxide is not the limiting factor; represented by y=ky = ky=k (where kkk is a constant)
From 0.02%0.02\%0.02% to 0.08%0.08\%0.08%; carbon dioxide is not the limiting factor; represented by y=mx+cy = mx + cy=mx+c (where m>0m > 0m>0)
From 0.14%0.14\%0.14% to 0.20%0.20\%0.20%; carbon dioxide is the limiting factor; represented by y=mx+cy = mx + cy=mx+c (where m=0m = 0m=0)
From 0.02%0.02\%0.02% to 0.08%0.08\%0.08%; carbon dioxide is the limiting factor; represented by y=ky = ky=k (where kkk is a constant)