Explanation

$C_{4}$-plants are more efficient in photosynthesis than $C_{3}$-plants but use more energy. They possess the larger number of chloroplasts in the leaf cells. In the leaves of $C_{4}$- plants, the vascular bundles are surrounded by bundle sheath of larger parenchymatous cells, which in turn are surrounded by mesophyll cells. Chloroplasts in bundle sheath cells are larger and always contain grana, whereas chloroplasts in mesophyll cells are smaller.