Which type of tissue is primarily responsible for protection, secretion, and forming boundaries?

Epithelial tissue is the correct answer because it serves several critical functions in the body, particularly in protection, secretion, and forming boundaries. This type of tissue covers body surfaces, lines cavities, and forms glands. Its dense cellular structure enables it to act as a barrier, protecting underlying tissues from mechanical injury, pathogens, and dehydration.

Epithelial tissue can also be specialized for secretion, as seen in glandular epithelia, which are responsible for the production of hormones, enzymes, and other substances. Additionally, it plays a crucial role in absorption and excretion, aiding in processes such as nutrient uptake in the digestive system.

The other types of tissue serve different primary functions. Connective tissue primarily provides support, binds other tissues together, and aids in transportation, such as blood and lymph. Muscle tissue is responsible for movement throughout the body, while nervous tissue is concerned with transmitting impulses and processing information. Thus, the unique structural features and functions of epithelial tissue make it essential for protection, secretion, and forming barriers.