( A ) C3 plants respond to higher temperatures with enhanced photosynthesis while C4 plants have much lower temperature optimum
( B ) Light saturation for CO2 fixation occurs at 10% of full sunlight
( C ) Tomato is a greenhouse crop which can be grown in CO2-enriched atmosphere for higher yield
( D ) Increasing atmospheric CO2 concentration up to 0.05% can enhance CO2 fixation rate