Question

which membrane lines the body systems that open to the outside?
serous
serosa
synovial
mucus

Explanation:

Serous membranes line closed body cavities. Serosa is another term for serous membrane. Synovial membranes line joint cavities. Mucus membranes line body systems that open to the outside such as the respiratory, digestive, urinary, and reproductive tracts.

Answer:

D. Mucus