Answer:
Covering organs within trunk cavities
Lining trunk cavities
Explanation:
Serous membranes are layers of tissue that protect the organs. They prevent the organs from getting damage from friction which can occur as they rub against the cavity walls.
Serous membranes have two layers, the visceral layer and the parietal layer. The visceral layer covers the organs while the parietal layer covers or lines the cavity walls. In between these two layers, you will find a gap or cavity filled with serous fluid.
They cover organs like the heart, lungs, blood vessels (some of them at least), testes and other organs found in the abdominal cavity.