Which of the following best describes the role of phloem in a tree?

Phloem plays a crucial role in the transport of food within a tree, specifically the products of photosynthesis, primarily sugars. These sugars are produced in the leaves during the process of photosynthesis and need to be distributed to various parts of the tree for growth, energy, and maintenance. The phloem tissue is responsible for conducting this food from the leaves to the rest of the plant, including roots, stems, and developing buds or fruit. This process is vital for the tree's overall health and ability to thrive, as it ensures that all parts of the tree receive the necessary nutrients for energy and growth.

The other options focus on functions that are associated with other parts of the tree: the xylem is responsible for transporting water and minerals from the roots, storage of nutrients is primarily a function of specialized cells or tissues within other areas of the plant, and structural support is provided by the sclerenchyma and xylem, particularly in the form of thick-walled cells and lignin. Thus, the role of phloem is distinctly centered on the movement of food substances throughout the tree.