The answer is: Chloroplasts.
True, a vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.
In C4 plants, photosynthesis is compartmentalized into two; light-dependent stage and light independent stage. The light-dependent stage occurs in the mesophyll cells of the leaf. Here, CO2 is fixed into oxaloacetate by PEP carboxylase enzyme. The oxaloacetate is then converted to malate that is then transported to bundle-sheath cells (around the leaf veins). The CO2 is then released from the malate and the gas molecule is subsequently fixed by RuBiSCO like in C3 plants. The biggest advantage of C4 photosytheis is that the wasteful process of photorespiration is greatly reduced.
I think its B but I'm not sure .. sorry