What are the three types of simple epithelial?

• A. Squamous, cuboidal, and columnar
• B. Columnar, cuboidal, and squamous
• C. Simple, stratified, and transitional
• D. Ciliated, non-ciliated, and goblet

Answer: (B)

The main idea is that simple epithelium is classified by the shape of the cells. There are three basic shapes: squamous (flat), cuboidal (cube-like), and columnar (tall). Any correct list of simple epithelia will include these three shapes, and the order doesn't matter, so listing columnar, cuboidal, and squamous covers the same set as squamous, cuboidal, and columnar. The other options mix in categories that aren’t the basic shapes of simple epithelia—one pairs by layering (simple vs stratified vs transitional) rather than shape, and the other describes surface features (ciliated, non-ciliated, goblet) rather than cell form.