The correct answer to the question is option 3: Xylem parenchyma.
The xylem tissue in plants is responsible for transporting water and nutrients from the roots to the rest of the plant. Xylem is composed of several different cell types, including tracheids, vessel elements, xylem fibers, and xylem parenchyma.
Option 1: Trachea refers to a type of cell found in animal respiratory systems and is not present in plant xylem. Therefore, this option is incorrect.
Option 2: Xylem fibers are responsible for providing structural support to the plant, but they do not carry out living processes. They are actually dead cells with thick cell walls. Therefore, this option is incorrect.
Option 4: Tracheids are elongated cells with tapered ends that are responsible for water conduction in gymnosperms and ferns. While they are living cells, they are not the only living tissue in plant xylem. Therefore, this option is incorrect.
Xylem parenchyma, on the other hand, is the living tissue within the xylem. These cells are responsible for various metabolic activities and play a role in the storage and transport of carbohydrates. They also