Final answer:
Most of the plant's body is composed of ground tissue, which performs metabolic functions, stores substances, and supports the plant.
Step-by-step explanation:
The plant tissue that makes up most of the plant's body is the ground tissue. Ground tissue carries out essential metabolic functions and is responsible for storing food and water. It is also involved in photosynthesis and provides support to the plant. Located in the interior of the plant, it surrounds the vascular tissue and is protected externally by the dermal tissue, which includes the epidermis, stomata, and guard cells. Vascular tissue includes xylem and phloem and is vital for the transportation of fluids within the plant. Together, these tissues play crucial roles in the plant's growth and survival.