Final answer:
The correct answer is 'a. Epithelial', as the epithelial tissue forms a protective boundary and is synonymous with skin, also called the cutaneous membrane.
Step-by-step explanation:
The type of tissue that acts as a protective boundary and is another name for skin is Epithelial tissue. This tissue, also known as epithelium, forms sheets of cells that cover the body's exterior surfaces, line internal cavities and passageways, and constitute certain glands. The skin, specifically, is a type of epithelial membrane called the cutaneous membrane and it features a layer of stratified squamous epithelial cells resting on connective tissue. The apical surface is exposed to the external environment and is protected by dead, keratinized cells that shield the body from various dangers like desiccation and pathogens. Therefore, the correct answer to the question is 'a. Epithelial'.