The graph shows the relation between light intensity and the giving off and taking up of carbon dioxide by the leaves of a plant. Why is most carbon dioxide given off when the light intensity is zero units [Kerala PMT 2004]

• A. Because it is just the start of the experiment
• B. Only respiration is taking place at this intensity of light
• C. Only photosynthesis is taking place at this intensity of light
• D. The rate of photosynthesis is equivalent to the rate of respiration
• E. The rate of photosynthesis is more than the rate of respiration