What is the outer layer of a serous membrane that lines a cavity?

• A. Visceral
• B. Mucosa
• C. Parietal
• D. Serosa

Answer: (C)

Two-layer serous membranes have a specific arrangement: the parietal layer lines the walls of a closed cavity, while the visceral layer covers the organs within that cavity. The space between these layers holds serous fluid to reduce friction as organs move. Mucosa is for mucous membranes that line open tracts, and serosa refers to the serous membrane in general rather than a specific layer. Since the question asks for the outer lining of the cavity, the parietal layer is the best fit.