Explanation: According to the graph, at 25 degree Celsius the rate of oxygen flow is maximum. Oxygen is a byproduct of the process of photosynthesis. So temperatures of 25 degree Celsius allow plant to photosynthesises more .
25 degrees Celsius, as this is the highest point on the graph which means that the oxygen flow is optimal at this temp. Since oxygen is a product of photosynthesis, if more is flowing at 25 degree, more photosynthesis is happening.