The source of $CO_2$ for photosynthesis during the day in $CAM$ plants is:

$C_4$ plants show adaptation to .........

In $C_4$ plants,the $C_3$ cycle takes place in:

Given below are two statements:
Statement $I$: The primary $CO_{2}$ acceptor in $C_{4}$ plants is phosphoenolpyruvate $(PEP)$ and is found in the mesophyll cells.
Statement $II$: Mesophyll cells of $C_{4}$ plants lack $RuBisCo$ enzyme.
In the light of the above statements,choose the correct answer from the options given below:

Agranal chloroplasts occur in certain

$C_4$ plants are more efficient in photosynthesis than $C_3$ plants due to the presence of: