What is the primary function of Phloem in vascular plants?

Phloem plays a crucial role in the vascular system of plants, primarily in the transportation of organic compounds, particularly sugars, from the leaves where they are synthesized during photosynthesis to other parts of the plant, such as the roots, stems, and developing fruits. This process is vital for the plant's growth and energy needs because the sugars serve as an essential source of energy and carbon for various metabolic activities.

While other tissues in the plant, such as xylem, function mainly to transport water and minerals from the roots to the rest of the plant, phloem specifically facilitates the distribution of the products of photosynthesis, ensuring that all parts of the plant receive the necessary carbohydrates for energy and growth. Thus, the primary function of phloem is accurately reflected in the correct choice regarding its role in transporting sugar down from the leaves.