All the grain legumes have a high photo respiration because of

Answer: Option A

When any photosynthetic plants yield 3-carbon acid or 3-phosphoglyceric acid (PGA) as their first product during the carbon dioxide fixation is termed as C₃ mechanism and C₃ plants.
Most C₃ plants have no special features to combat photorespiration. The first step in the Calvin cycle is the fixation of carbon dioxide by Rubisco, thus all the grain legumes have high photorespiration because of the C₃ mechanism.