Answer:
The correct answer is option c. "old layers of xylem and phloem".
Explanation:
Wood is one important good used for construction obtained from the main substance of the outer layer of the trunk or branches of a tree. Biologically, the outer layer of the trunk of a tree is comprised of the old layers of xylem and phloem, which are dead cells that were part of the heartwood or the centre of the tree. These old layers of xylem and phloem form the outer bark structure of the tree.
