The main function of the stem in a plant is A. transporting nutrients and water to the leaves.
The stem acts as a crucial conduit between the roots and the leaves. It is responsible for the upward movement of water and essential nutrients absorbed from the soil through the roots. The stem’s vascular system, which includes xylem and phloem, allows for this transport. The xylem carries water and dissolved minerals from the roots to the leaves, where photosynthesis occurs, while the phloem distributes the sugars produced in the leaves to other parts of the plant.
While the stem does have other roles, such as providing support and storing nutrients, its primary function centers on the transportation of these vital resources. Thus, options B, C, and D, although related to plant functions, do not capture the central role of the stem as accurately as option A does.