Option 1 (Cutin) -> A waxy substance found in the cuticle of leaves and stems, not in cork cells.
Option 2 (Lignin) -> A complex polymer that provides rigidity to plant cell walls, mainly in woody tissues, not specific to cork.
Option 3 (Suberin) -> A waxy, waterproof substance deposited in the cell walls of cork cells, making them impermeable to water and gases.
Option 4 (Cuticle) -> A protective outer layer of plants, not a substance contained within cells.
Hence, Option 3 (Suberin) -> Cork cells, which are dead cells forming the protective outer bark layer, have their cell walls impregnated with suberin. This waxy substance makes cork impermeable to water and gases, providing excellent protection and insulation to the plant. -> correct