Which of the following is not one of the primary germ layers?

• A. Ectoderm
• B. Mesoderm
• C. Endoderm
• D. Epidermis

Answer: (D)

Verified step by step guidance

1. Understand the concept of germ layers: Germ layers are the primary layers of cells that form during embryonic development. They give rise to all tissues and organs in the body.
2. Identify the primary germ layers: The three primary germ layers are ectoderm, mesoderm, and endoderm.
3. Ectoderm: This layer forms the outermost layer and gives rise to structures such as the skin and nervous system.
4. Mesoderm: This middle layer forms structures such as muscles, bones, and the circulatory system.
5. Endoderm: This innermost layer forms the lining of the digestive and respiratory systems. Epidermis is not a germ layer; it is derived from the ectoderm.