In the cross section of trunks of large trees, a central dark region called heartwood is observed.It is significant to plants because it

Explanation

Heartwood is the central, dark region in the cross section of a tree trunk. It is primarily dead tissue that no longer conducts water but provides structural support. Its resistance to insect and fungal attacks is due to the accumulation of chemical compounds such as tannins. In contrast, the other options describe functions of the sapwood or outer layers of the tree: bark formation is related to the outer cambium layers, translocation occurs in the phloem, and the ascent of sap involves active xylem.