The germinal epithelium is a specialized type of epithelial tissue that lines the surface of the ovary. It plays a crucial role in the development and maturation of ovarian follicles, which are responsible for the production of eggs.

The correct answer to this question is option 'A', cuboidal epithelium. Let's understand why this is the correct answer in detail.

**Germinal Epithelium:**
- The germinal epithelium is the outermost layer of cells that covers the ovary.
- It consists of a single layer of cuboidal epithelial cells.
- These cells are tightly packed and form a protective barrier around the ovary.
- The cuboidal shape of the cells allows for efficient absorption and secretion of substances.

**Epithelial Tissue:**
- Epithelial tissue is one of the four main types of tissues found in the body.
- It covers the outer surfaces of organs, lines the body cavities, and forms the lining of blood vessels and respiratory, digestive, and reproductive systems.
- Epithelial tissue is classified into different types based on the shape and arrangement of the cells.

**Types of Epithelial Tissue:**
1. Squamous Epithelium: Squamous epithelium consists of thin, flattened cells that resemble scales. It is found in the lining of blood vessels, alveoli of the lungs, and the outer layer of the skin.
2. Cuboidal Epithelium: Cuboidal epithelium consists of cube-shaped cells with a centrally located nucleus. It is found in the lining of glands, kidney tubules, and the germinal epithelium of the ovary.
3. Columnar Epithelium: Columnar epithelium consists of tall, elongated cells with a nucleus located near the base. It is found in the lining of the intestines, respiratory tract, and parts of the reproductive system.
4. Glandular Epithelium: Glandular epithelium is specialized for secretion and is found in glands throughout the body. It can be classified into exocrine and endocrine glands.

**Why Cuboidal Epithelium is Correct:**
- The germinal epithelium is composed of cuboidal epithelial cells.
- The cuboidal shape of the cells is well-suited for the function of the germinal epithelium, which is to protect and support the developing ovarian follicles.
- The cuboidal cells provide a larger surface area for absorption and secretion of nutrients and hormones necessary for follicular development.
- This arrangement allows for efficient exchange of substances between the ovary and the surrounding tissues.

In conclusion, the germinal epithelium is composed of cuboidal epithelial cells. These cells form a protective barrier around the ovary and play a crucial role in the development and maturation of ovarian follicles.