Answer: The structure labelled as 'x' is the phloem.
Its function is to transport (move) water from roots to rest of the plant.
Explanation:The diagram depicts the cross-section of a stem. The xylem and phloem that make up the vascular tissue of the stem are arranged in distinct strands called vascular bundles.
Phloem tissue is composed of sieve-tube cells, companion cells, phloem parenchyma, and phloem fibers. A series of sieve-tube cells (also called sieve-tube elements) are arranged end-to-end to create a long sieve tube, which transports organic substances such as sugars and amino acids. The sugars flow from one sieve-tube cell to the next through perforated sieve plates, which are found at the end junctions between two cells. Although still alive at maturity, the nucleus and other cell components of the sieve-tube cells have disintegrated. Companion cells are found alongside the sieve-tube cells, providing them with metabolic support. The companion cells contain more ribosomes and mitochondria than do the sieve-tube cells, which lack some cellular organelles.