The main function of epithelial tissue is:

(C) Defense

Explanation:

Epithelial tissue serves as a protective covering for the body and its organs. It acts as a barrier that helps prevent the entry of pathogens and other harmful substances. Epithelial cells are tightly packed and form continuous sheets, providing a protective layer on the body surfaces, both internal and external. This protective function is essential for defending the body against infections and maintaining its integrity. Therefore, option (C) Defense is the correct answer.