Which tissue forms sheets that cover the inside and outside surfaces of the body, including the outer surface of the skin and linings of internal organs?

• A. Nerve Tissue
• B. Muscle Tissue
• C. Connective Tissue
• D. Epithelial Tissue

Answer: (D)

Epithelial tissue creates continuous sheets that cover both the outside and inside of the body. It forms the outer layer of the skin (the epidermis) and lines the linings of internal organs, cavities, and ducts, providing protection and participating in absorption, secretion, and filtration. This tissue is tightly packed and sits on a basement membrane, often forming a barrier that is avascular and highly regenerative. Epithelia can be classified by layers (simple vs stratified) and by shape (squamous, cuboidal, columnar), which helps explain how they function across different surfaces. Other tissues—nerve for signaling, muscle for movement, and connective for support and binding—do not form those continuous surface sheets in the way epithelial tissue does.