We have that there are 5 main tissue types in most vertebrates: epithelial, connective, nervous and muscle tissue. It is clear that muscle tissue helps the movement of various parts of the body and it is not dound in the skin. Also, interstitial tissue is the name with which we refer to extracellular fluids like blood plasma and thus this is wrong too (sweat is not a type of tissue). Nervous tissue is also deep under the skin. Connective tissue is the tissue that connects other types of tissues with the bones etc.; for example there is conenctive tissue in the brain. Finally, the correct answer is epithelial; they form the outermost layers of our cell structure and they serve to protect the rest of the tissue as well as provide us with sensations from the outside.