Answer:
a. numerous blood vessels
Explaination:
Epithelial tissues are composed of cells laid out in sheets with the strong cell to cell attachments. These protein connections hold the cells together to form a tightly connected layer that is avascular but innervated in nature. Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport and sensing. Epithelial layers contain no blood vessels, so they receive nourishment via diffusion of substances from the underlying connective tissue through the basement membrane. Epithelium covers nearly all external and internal body surfaces.
