Final answer:
The basal lamina is a thin extracellular layer that underlies epithelial cells, separating them from other tissues and serving as an attachment site.
Step-by-step explanation:
The basal lamina is a thin extracellular layer that lies underneath epithelial cells and separates them from other tissues. It is part of the basement membrane, which in epithelial tissue is a thin layer of fibrous material that anchors the epithelium to the underlying connective tissue. The basement membrane is made up of the basal lamina and a reticular lamina. Specifically, the correct answer here is that a basal lamina is a thin layer of ECM underlying an epithelium. It provides an attachment site for the epithelium, separating it from the underlying connective tissue. Also, anchoring junctions, such as hemidesmosomes, help link epithelial cells to the basal lamina, contributing to cellular stability.