Which of the following tissues primarily serves as a protective barrier in the body?

Epithelial tissue is primarily responsible for serving as a protective barrier in the body. This tissue type covers the surfaces of the body, both inside and out, forming a protective layer that safeguards underlying structures from mechanical injury, pathogens, and harmful substances. It also plays an essential role in absorption, secretion, and sensation.

Epithelial tissue can be found lining organs, blood vessels, and the skin, where it serves not only as a barrier but also assists in regulating permeability and facilitating interactions between the body and its external environment. Given its crucial role in protection and boundary formation, it is the prominent tissue that fulfills this function within the human body.