Which one of the following is a xerophytic plant in which the stem is modified into the flat green and succulent structure?

Opuntia is a plant growing in dry and xeric habitats and it has a stem containing several nodes and internodes. It is modified into a flat, fleshy and thick green leaf-like structure called phylloclade. which performs the functions of photosynthesis. The leaves gets modified into spines to help in reducing transpiration.