A)It is continuous with the atmosphere and protects the lungs from infection. B)It is a closed sac surrounding each lung that contains only a tiny volume of lubricating fluid. C)It is a closed sac surrounding each lung and contains a large volume of surfactant. D)It is a closed,air-filled space surrounding both lungs that has a negative pressure compared to atmospheric pressure. E)It is bounded by pleural membranes that are very thin,which allows for abundant gas exchange.