The correct option is D Parenchyma
Xylem is a complex permanent tissue. It is composed of xylem tracheids, xylem vessels, xylem fibres and xylem parenchyma. The tracheids, the trachea, and the xylem fibers are non-living components, while xylem parenchyma represents the only living component of the tissue
Thus, the correct answer is option D.