Task: Class Definition Understanding (ontology: Earth_Environment/EnvironmentOntology)

Which of the following definitions best describes 'epithelium of mucosa'?

A. An epithelial sheet bent on a linear axis.
B. An epithelium consisting of cuboidal epithelial cells.
C. An epithelium that lines the lumen of the digestive tract.
D. A layer of epithelial cells on the surface of the mucosa.

Answer: A layer of epithelial cells on the surface of the mucosa.