What is the main function of phloem in plants?

Phloem's primary role in plants is to transport sugars and organic substances produced during photosynthesis from the leaves to other parts of the plant where they are needed for growth, storage, and development. This process, known as translocation, is vital for maintaining the plant's energy balance since the sugars provide essential nutrients that fuel various metabolic activities.

In contrast, the transport of water is primarily managed by xylem, which carries water and minerals from the roots to the stems and leaves. Nutrient storage is typically associated with different plant structures, such as roots or seeds, rather than phloem. While plants have protective mechanisms, such as bark or thorns, these are not functions of phloem but rather serve to guard against herbivores and diseases. Thus, the correct answer highlights the critical contribution of phloem to the overall nutrient distribution system within plants.