Since we are looking for a single layer of cells, we must rule out any area of the body that is subject to lots of friction. The skin is continually being rubbed and pushed by everything we touch, and the esophagus sustains abrasions from all the food we eat.

Microvilli are tiny projections on the apical surface of cells that increase the cell surface area. Since most of the absorption of food and nutrients occurs in the small intestine, it makes sense that we would want to increase the surface area of that region. Furthermore, since we are absorbing, we would want a single layer of cells to facilitate the diffusion of substances across the layer of epithelium. Thus, the correct answer is that simple columnar epithelium with microvilli will be found in the small intestine.

All of these areas of the body are subject to lots of friction. Thus, there would be multiple (stratified) layers of epithelium lining them.

An epithelia is a sheet of cells that are closely associated. Cells within an epithelium are polarized, indicating that the cells have a "direction". One side of the epithelium is called "apical" while the other side is "basal." The apical region is oriented toward a lumen, while the basal region is oriented toward a basement membrane associated with connective tissue. Cells within an epithelium are innervated, but not vascularized; therefore, they must receive signals through other methods of intercellular signaling, such as tight junctions.

The epidermis is composed of five layers of flattened epithelial cells. This stratified squamous epithelium allows the skin to be a barrier for the body and prevent pathogens and foreign materials from entering.

Stratified epithelium has multiple layers, and squamous epithelium is flattened.

Nervous tissues such as the brain, spinal cord, and nerves function to transmit impulses for coordination, sensory reception, and motor actions. Epithelial tissue protects (skin), secretes (glands), absorbs (kidneys), and produces germ cells (embryo).

Epithelium describes the inner and outer surfaces of the body including; the skin, colons, and the stomach. These surfaces have distinct upper and lower sides, are kept in place by connective tissue, and are made up almost entirely of cells. However, they are not supported by blood cells. 

The primary function of epithelial tissue is to provide linings that separate the body from the external environment. Epithelial tissue lines blood vessels, the respiratory and digestive tracts, the excretory system, and composes the skins. Epithelial tissue also lines the ducts that connect the body to the exterior, such as those that allow the pancreas to secrete enzymes into the small intestine.

Epithelial tissue is avascular (does not have a blood supply); thus epithelial tissue is always found in close association with connective tissue that has a rich blood supply. Epithelial cells cover organs and are thus subject to lots of friction. As a result they are continually being renewed, and divide quickly. In particular, skin cells and the epithelium lining the digestive tract have a high rate of division.

Adipose tissue is the anatomical term assigned to fatty tissue. Keep in mind that adipose tissue is a type of connective tissue. Adipose tissue serves as an energy store, helps maintenain of core body temperature, and protects internal organs from damage caused by trauma. Epithelial tissue is responsible for covering body cavities, and comprising glandular tissue. Nervous tissue is responsible for receiving sensory input from the environment, integration of the sensory input, control of muscles and glands, maintenance of body homeostasis, and emotions/personality. Smooth and striated are subsets of muscle tissue: skeletal and cardiac muscle are striated, whereas smooth muscle is not.

The endothelium is a form of squamous epithelium consisting of flat cells that line the blood and lymphatic vessels. Endothelial cells are metabolically active and produce compounds that relax vascular smooth muscle and inhibit the adhesion of platelets.

Adipose, or fat cells, are modified for long-term energy storage and are considered connective tissue. Cone cells are found in the eye and serve as light receptors for the nervous system. Stem cells can develop into more specifically differentiated daughter cells. Dendritic cells help T-cells respond to foreign antigens as part of the immune system.