If we keep on increasing CO₂ concentration in air what will be the rate of photosynthesis? (AS2)

Carbon dioxide is an important component of photosynthesis. In general, an increase in the carbon dioxide levels increases the rate of photosynthesis. There is a linear increase in the rate of photosynthesis with increase in the carbon dioxide (Fig 5). However, an increase in carbon dioxide beyond the threshold does not affects the rate of photosynthesis (Fig 5).

Fig 5 shows relation between the rate of photosynthesis and carbon dioxide