The cactus has a specialized fleshy stem and it's leaves function only for protection. Which plant tissues most likely makes up the stem?

If I am not mistaken, the plant tissues that most likely make up the stem is "Vascular."

The stem is most likely made up of vascular tissues. The main vessels present on vascular tissue are the xylem and phloem. These two tissues work as pipes for the transport of water and nutrients inside the stem. Xylem transports water and some nutrients from the roots. The Phloem transports the soluble organic compounds that were produced during photosynthesis from the leaves, and in the case of the cactus photosynthesis happens on the actual stem, to the rest of the plant.