**Core Concept**
The protective epithelium, also known as stratified squamous epithelium, is a type of epithelial tissue that forms the lining of various body surfaces, including the skin, esophagus, and oral cavity. Its primary function is to provide a physical barrier against external factors such as mechanical trauma, chemical irritation, and infection.

**Why the Correct Answer is Right**
The protective epithelium is characterized by multiple layers of cells, which allows for the constant shedding and renewal of cells. This process helps to maintain the integrity of the epithelial barrier and prevent damage from external factors. The cells in the protective epithelium are also tightly packed together, which further enhances their protective function. This tight packing also allows for the formation of desmosomes, which are strong intercellular junctions that help to hold the cells together.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the characteristic of pseudostratified columnar epithelium is that it appears stratified under a microscope, but all the cells are actually in contact with the basement membrane.
**Option B:** This option is incorrect because the characteristic of simple cuboidal epithelium is that it has a single layer of cuboidal cells, which is not representative of the protective epithelium.
**Option C:** This option is incorrect because the characteristic of simple columnar epithelium is that it has a single layer of columnar cells, which is not representative of the protective epithelium.

**Clinical Pearl / High-Yield Fact**
The protective epithelium is also known as stratified squamous epithelium because it is composed of multiple layers of squamous cells. This type of epithelium is found in areas of the body that are exposed to mechanical stress, such as the skin and esophagus.

**Correct Answer:** D.