The correct option is: (a)
Explanation:
C4 plants are more efficient than C3 plants because they have little photorespiration while in C3 plants more than half of photosynthetic carbon get lost in photorespiration. C4 plants are more efficient in picking up CO2, even in low CO2 concentration because of high affinity of CO2 with PEP (phosphoenol pyruvic acid).
Presence of photorespiration is considered as a wasteful and energy consuming process in crop plants which ultimately, leads to reduction in final yield of crops. It is estimated that during C3 photosynthesis, upto 50% of the CO2 fixed may have to pass through photorespiratory process, thereby resulting in considerable decrease in photosynthetic productivity. In C3 plants, there is loss of photosynthetic activity on account of photorespiration which is absent in C4 plants and hence they have better productivity.
