Difference between heartwood and sapwood is that heartwood

The correct option is "has dead and non-conducting elements".

To understand why this is correct, let us look at the differences between heartwood and sapwood in a woody stem:
During the secondary growth of a woody plant, the older xylem elements towards the center of the stem become modified to form heartwood (duramen), while the outer functional xylem forms sapwood (alburnum).

As the stem grows in girth, the central region of secondary xylem ceases to transport water and minerals. This occurs because the vessel elements and tracheids become clogged with tyloses (outgrowths of parenchyma cells) and are infiltrated with organic compounds such as tannins, resins, oils, gums, and aromatic substances. These substances make the wood dark, hard, and highly resistant to decay and pathogens.

Consequently, heartwood contains dead cells and does not participate in the conduction of water or minerals. Its primary function shifts to providing mechanical support to the tree. In contrast, the outer sapwood remains physiologically active, contains living parenchyma cells, and actively conducts water and nutrients from roots to leaves.

Therefore, the key distinguishing feature of heartwood compared to sapwood is that heartwood has dead and non-conducting elements.