What is a characteristic function of epithelial tissue?

Epithelial tissue is primarily known for its role in covering and lining various surfaces of the body. It serves as a protective barrier and is involved in various functions such as absorption, secretion, and sensation. The characteristic feature of epithelial tissue is its ability to form sheets that line surfaces, whether they be external (like the skin) or internal (like the lining of the gastrointestinal tract, respiratory pathways, and blood vessels). This function is critical for maintaining the body's integrity and facilitating interactions with the environment.

Additionally, the other options describe functions associated with different types of tissues. For instance, the formation of bone tissue is a characteristic of connective tissue, while the production of red blood cells occurs in bone marrow, which is also classified as a type of connective tissue. Protection of internal organs is a broader function that could involve multiple tissue types, but it does not specifically highlight the unique functions of epithelial tissue as the covering of surfaces does. Thus, the correct answer accurately reflects a fundamental property of epithelial tissue.