Answer:
obtain and use energy (Ans. D)
Explanation:
Photosynthesis: It is the process where plants and some other organisms use the energy from sunlight to make sugar which converts cellular respiration into ATP.
Cactus plants have pads, succulent stems with spines and scales instead of leaves. In cacti plants photosynthesis occurs in stems through a special mechanism called Crassulacean acid metabolism (CAM) as a part of photosynthesis.