Answer:
Most correct answer is all of the germ layers
Step-by-step explanation:
Mucous membranes constitute the innermost layer of a number of hollow organs (i.e.: gastrointestinal tract). They are composed of an epithelial lining which overlies a deeper layer of connective tissue. Typically, each of these components arises from a different germ layer. For instance: the mucous lining of the gut arises from a combination of endoderm-derived epithelium and lateral mesoderm-derived connective tissue. Other mucous membranes may have different origins, for example: The mucous lining of the oral cavity is composed of ectoderm-derived epithelium and underlying connective tissue derived from head mesenchyme (combination of cephalic neural crest and paraxial mesoderm).
Summary:
Mucous Membrane = Epithelium (derived mainly from endoderm, followed by ectoderm, rarely mesoderm) + Underlying Connective Tissue (usually mesoderm)