The answer is D because that’s the only way the cactus would survive.
Have you ever wonder on how cactuses survive in a desert? and be clear that deserts is a biome that contains no water, and it’s just dry and hot. Well, since you know that a cactus is a plant, and a plant needs chlorophyll (I think that’s how you spell it) to survive, if not, it will die. So, in order for the cactus to survive, it would need to have water inside its vacuole.