Question

why epithelial and cork cell are called protective tissue?

Answer 1

cork cells are dead and do not have any intercelluar spaces. The cell wall is coated with suberin . It protects the underline vessels.
when skin cells get damaged it is replaced by another layer of epithelial tissue
therefore it is known as protective tissue

Answer 2

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Epidermis is the first layer of the body of both plants and animals that acts as the first line of defense against various types of harmful objects. It protects the other parts of the body from injuries, bacterial attacks etc.

For this reason, epidermis is known as protective tissue.