A student investigated the effect of carbon dioxide concentration on the rate of photosynthesis in pondweed at a constant light intensity and temperature. The results of this investigation are shown in the graph below.
Which range of carbon dioxide concentration represents a region where carbon dioxide is no longer the limiting factor of photosynthesis, and the rate can be mathematically modelled by the equation y=ky = ky=k (where k>0 k > 0\,k>0 is a constant)?
0 to 300 ppm0\text{ to }300\text{ ppm}0 to 300 ppm
300 to 600 ppm300\text{ to }600\text{ ppm}300 to 600 ppm
600 to 1000 ppm600\text{ to }1000\text{ ppm}600 to 1000 ppm
0 to 600 ppm0\text{ to }600\text{ ppm}0 to 600 ppm